Yes, or you can calculate it based upon the thermal dissipation needs of the processor. The main challenge being estimating what the temperature in the case is going to be when the processor is at full capacity and the room is already warm.

http://computer.howstuffworks.com/heat-sink3.htmhttp://computer.howstuffworks.com/heat-sink3.htm

Although for a beginner, I'd definitely be cautious and stick to whatever the manufacturer recommendations. Ideally the case itself would have ducting to lead the air out of the case directly after leaving the heatsink.

The full list of components you'll need to have a functional computer are as follows:
CPU
Motherboard
RAM
Power Supply
Graphics Card
Case
Hard Drive
Optical Drive (DVD)
Operating System (e.g. Windows)
Peripherals (monitor, keyboard, mouse, speakers)

Cases will come with several fans already built in, and typically you won't need to add any additional ones unless you plan on overclocking or you find that for some reason your rig is running quite a bit hotter than you'd prefer.

As has been mentioned, Newegg is the best option out there if they can ship to you. If you put it together yourself it can be a fun and rewarding experience, although it can take a bit of time the first time through. Also, if you build it yourself I'd recommend getting yourself a static strap (they run about $5) so that you don't end up turning a $200 component into a paperweight just because you shuffled your feet a bit too much on the carpet. Alternatively, there are a fair number of companies that will assemble a computer to your specifications- these sites allowing for varying degrees of selection of the components used, although in all such cases you'll have less of a selection than if you assembled it yourself. You'll also need to be careful as most of these companies like to skimp on the quality of the motherboard and power supply; if they don't specifically list the supplier and model assume they're going to use the cheapest POS that's capable of working with the rest of the components.

Okay, this might sound stupid, but after looking around on newegg there seems to be a never ending list of various types of video cards. What's the difference between Asus, XFX, HIS, MSI, and all these others? Are these the brands? I thought Nvidia and ATI were the brands, or are those just the software that runs the video card hardware? Sorry I'm so new at this.

My understanding is that Nvidia and AMD/ATI are the chipset manufacturers- they're the ones who design and produce the actual microprocessors that are at the heart of the graphics card. Asus, XFX, MSI, etc are the ones who then buy those chipsets and attach them to the rest of the graphics card that they've manufactured. (Someone feel free to correct me or fill in any details I missed or got wrong).

The chipset designers also design the "reference" cards. Because most card makers simply use the reference design, the cards usually differ little from manufacturer to manufacturer.

Cooler design and warranty service are the main differences. Some makers (MSI is one) have unusual cooler designs that may run quieter or cool more efficiently than the standard cooler. Some makers (EVGA and XFX stand out) have generous or special warranty terms that are worthwhile if you plan to overclock or to keep the card for a long time.

Thank you everyone! You've been very helpful in making my decisions easier. For right now, I've just got a few questions about computer accessories.

I'm assuming I don't need a fancy, expensive gaming keyboard and mouse to play games, right? Cause that would be alot of money saved. I've only used a laptop for the past four years while in college, and I'm used to a smaller laptop mouse. Would that work fine for most games?

I know absolutely nothing about motherboards. What kind of qualities am I looking for in one? I'm guessing that's one area I don't want to go cheap on...

And last: what kind of monitor is best? Or does it really matter? I've seen a big price difference in some screens, so I don't know if some are better for gaming than others.

No, you definitely don't need a fancy, expensive keyboard and mouse, but on the other hand you don't want to completely cheap out on them either. What you should do is take a close look at the actual design and layout of keyboards and mice to see if anything specifically appeals to you, and also look at customer reviews with a focus on things like comfort and durability (e.g. for some the letters will start wearing off after just 6 months of use, while others will last for years before any wear and tear becomes evident, and thing like this don't even necessarily track with price).

First off decide what CPU you're going with, as this will determine what motherboards you'll need to chose from (specifically the motherboard will need to have the same socket as the CPU you're getting, then also double-check the motherboard specifications to ensure that it supports the specific processor you're getting). Next you'll want to ensure you're getting one with a good chipset- for example if you're going with a Core i5 or i7 (socket LGA 1155), then the Z68 chipset is a good one to look for. You'll also want to make sure that the motherboard has expansion slots for any cards you intend to put in (e.g. PCIe-x16 for a graphics card). Finally look through user reviews focusing on reliability (e.g. what percentage got DOA motherboards, or had them fail after several months) as well as comments on layout (some motherboards put things in weird places that make hooking everything up a bit more difficult than it should be).

What kind of monitor is best? A big one. ;) But seriously, the main thing you'll be looking at is size and resolution. No pointing building a kickass PC if you're then just running things at 1280x720 because that's all your monitor can handle. And again, also look at user reviews to spot differences in reliability between similar monitors from different manufacturers.

1/ You need to be comfortable with your keyboard and mouse. True "gaming" KB and mouse are mostly just marketing hype. But it's worth considering something above the entry level. A 12 USD Gygabyte KB will probably be worth the 6 USD above the entry level thing. As for the mouse, all depends on the size of your hand...

2/ Always go for a reputable manufacturer (Gigabyte, MSI, Asus ) . You don't want to consider the top of the range as again there is a lot of marketing hype. But the middle range usually has the features you really want ...

3/eyes are quite precious. I would say a Samsung or LG led screen... size depends on the space you will have between your eyes and your screen. In a cramped space, don't take too large a screen. 21 / 23 inchers usually fit all needs.

If you have a keyboard and mouse you are already happy with you might as well continue using them. My keyboard is so old it has the Windows 95 logo on the Windows key. I probably won't give it up until the day they stop putting PS/2 ports on motherboards. :D

The same can apply to the monitor, speakers, and other external goodies unless you're wanting a higher resolution or better sound quality or whatever.

There are Y-shaped cables that allow you to plug two fans into one connector, so don't worry about that too much. This will force both fans to spin at the same speed, but I reckon this won't be a problem so long as these fans are performing the same function (intake/intake or exhaust/exhaust).

There are many kinds of fans to choose from, all of them with their pros and cons. Generally speaking, cheap fans have simple bearings that won't last as long and/or will produce more noise than expensive ones. Fast-spinning fans move more air but are noisier. I think you should restrain yourself from buying extra fans in the beginning; you can get them later on if the rig is running hot and you think you can bear with the increased noise. My nerdier friends seem to agree that exhaust fans can be of a slower variety than intake, and that intake should be always be a priority. They do have a point; if you want to cool down a cup of coffee, do you blow on it or try to suck the heat off?

Some stores will do it for you, but they might ask a gargantuan pile of money for it.

Probably not. I have a Microsoft Sidewinder X6, which is a gaming keyboard, but I don't think I've ever used any of its gaming features (such as macro buttons). Gaming mice often have a few nice features (such as five buttons) and a heap of completely unnecessary ones (such as a Razer logo) that hike up the price. If you're going to buy a gaming mouse, make sure it has a proper warranty as well; it would really suck to buy an expensive mouse that only lasts fourteen months. I know because I've done it.

Internal speakers tend to have substandard sound quality, so avoid those. Apart from that, just make sure it's HD (1920x1080 or 1920x1200) and has a DVI and/or HDMI port. LCD monitors are cheaper whereas LED's consume less power and produce sharper colours IIRC. Can't really think of much else since differences between displays are pretty minimal.

"Gaming" keyboards and mice are overrated, and the magic buzzword "gaming" tacks $10 or more onto the price. Get a keyboard and mouse that are comfortable for you.

The ones I use all day, every day, are a Microsoft "Digital Media Pro" keyboard and a Logitech "Marble" trackball. I prefer trackballs to mice, but YMMV.

For motherboards, you need to consider a few things:

1. Compatibility with the CPU. Each motherboard has a specific socket type and a specific set of CPUs it will work with. The manufacturers publish these on their Web site. Usually I choose the CPU I want, then choose a motherboard that is compatible with it.

2. Bells and whistles. Many of the features of your computer are actually part of the motherboard: USB, audio, Firewire (if you have a camcorder, you may need it), SATA ports for your disk drives. Be sure the motherboard has all the provisions you are going to need.

3. Manufacturer. ASUS is number one. MSI and Gigabyte are close seconds. All the others are behind them, at least in terms of reliability. Of the others, ASRock and Biostar have some innovative features that come in handy in specific applications.

For a monitor, it must be easy on your eyes for long periods of time. For size, usually this means 24-inch if you go with the full 1920x1080. The best picture quality and color range are foind on "IPS" monitors. These cost more ($100 or so more) than the common cheap "TN" monitors. If a monitor is IPS, it will usually say so in the fine print. If you do digital photography or video, or any professional or serious amateur work requiring accurate color, an IPS monitor is a must. If your most demanding use is playing games and surfing the Web, and budget is important, there are perfectly good TN monitors that will take less out of your pocket.

Does anyone know much about the AMD FX6100 Zambezi processor? At a cursory glance, it looks like it's better than the i5-2500, and has more cores. That's a good thing, right? But it's 50 dollars less than the Intel processor. That makes me wonder if it's any better. It has some really favorable customer reviews too.

http://www.newegg.com/Product/Product.aspx?Item=N82E16819103962

It's slower in single threaded usage (games) equal or faster in optimised multithreaded BUT is crippled by current windows schedulers and apparently runs much better with windows 8. Wait till ivybridge and piledriver are out both are apparently faster than current chips and due out over the next few months.

Not better as in better performance, but at least good performance for the price. Reviews on Newegg are not that telling, because they are just anecdotes, not controlled testing. On controlled tests, the Sandy Bridge Core i5 and Core i7 CPUs consistently beat any AMD CPU (with the exception of the somewhat slower Core i5 2400, which is about equal to the AMD CPUs).

AMD's CPUs are almost always better value than Intel's, but Intel still dominates the high-performance end of the CPU market.

AMD's new CPUs are not able to reach their full potential on Windows 7, because the scheduler doesn't use them optimally. Microsoft tried to fix the Windows 7 scheduler for them, but was unable to do so (and withdrew the patch). They will be a lot better on Windows 8.