Anyone good at building their own desktops? I'm thinking about upgrading my mobo/cpu/memory, but I'm not sure whether my power supply will have to be replaced as well. I'm thinking about getting a AMD Phenom II X4 3.0 gig 95W processor, mobo still up for debate, and putting in 4 gigs of DDR3 1600. My current powersupply is 450W, would that be enough or should I look at getting an upgrade? My current graphics card is a EVGA 8800GS, probably upgading that somewhere down the line when I have more money again.

It should be enough. Unless you have numerous drives and a demanding GPU.

It really depends on the quality of the power supply. The most used voltage rail is 12V unfortunately most generic power supplies still only supply half the power rating there, this may give you somewhere around 250W's to play with on yours.
Dealing more directly with your case if you don't change your graphics card to something with higher power requirements you will be fine with the supply you have.

Yea, considering I have one hard drive and one optical drive, I should probably be good... that powersupply is pretty decent, its been going strong for over two years. I guess if I do need to replace it its not a big deal, just rather not mess with it if not needed. Thanks.

Egotomb has a point. What brand is it? Only unbranded ones might not only fail to meet demands, but also are unreliable. The thing most likely to cut a component's lifespan short is a crappy PSU.

Top of my head I don't remember, I'll have to look it up when I get home

If you've already been running this thing for two years with no problems, then it is reliable, it doesn't matter what brand it is. As for if it is good enough, a 450 should be OK for that hardware, but a 500 or higher would be more "future proof". The question becomes, do you plan on regularly upgrading this machine? If yes, then it might be worth it to go overboard with the PSU now so that you don't have to worry about it down the line. If no, then stick with what you got.
BTW - Replacing the PSU is probably one of the easiest components to deal with. Motherboard and hard drive/component power connectors are standard across all makes and models and do not change very often. Its not like dealing with a processor or RAM upgrade, where you have to make sure to get the right slot type and those slot types change every 18 months or so.

You should be just fine using your old PSU. There's not really enough variation in the amount of power that motherboards and RAM draw to even be worth considering, and while at 95 W the Phenom II is a pretty power hungry CPU (most weigh in around 60 W), your power requirements increasing by 30-40 W or so isn't going to start causing you problems if you've been running just fine for a couple years already.

I probably won't upgade this for at least 2 years from now, maybe with the exception of a new graphics card. If I have to upgrade the PSU at that point I will, but I'm on a budget and would rather not mess with it right now if not necessary. Thanks all for the info, I think I got what I need.

Rule of thumb applies here : "the bigger the better!" :D.

Only if you don't need to worry about electricity costs, no need to have a 1000w sli ready psu for a single 8800, quadcore system.

Trying to keep this stuff to this thread. Ahhhh

o, didn't realize we had one of those, will do for the future. consider thread closed!

A 1000 watt power supply won't take more electricity than a smaller one unless the efficiency numbers are bad. A power supply only draws what it needs to run the hardware. Good power supplies that are "80 Plus Certified", will maintain 80% efficiency from 50 watts to 90% of their rating.

With power supplies it's much better to aim for quality over quantity. Getting a cheap 1000 W PSU just means that when it blows you've now got that much more power surging through your system frying other components. While you naturally want enough power for all your components plus a bit to spare, once you've got that any extra spent on a PSU is better spent making sure that it's from a reputable manufacturer that uses quality components and that it actually performs within specs.