Depends what you mean by "vanilla". I don't recommend playing with no unofficial mods or patches whatsoever, simply because some of those are merely fixpacks that fix bugs and the like without adding any new content or changing the game rules. If you're happy to have those (and there's really no reason not to), the sticky threads on this board, "A Conservative Modder's Guide to Baldur's Gate 1" and "Baldur's Gate 2 essential mods", are very good - follow those and you can't really go wrong.

The above only applies to the original versions, not the Enhanced Editions (the two now come as one package for each game and are not available separately); I haven't played the Enhanced Editions myself so I can't advise you on those.

Where can I find such a fixpack? The only fixpack I know of, as required "fix"es (as in, you can't choose to disable them while still using the rest of the fixes), changes the rules by, for example, making certain effects not stack (when they do stack normally).

(This sort of reason is why I will not play with such a fixpack installed.)

It's absolutely possible to play both games vanilla, and without any mods or fixpacks, if that is what you wish. I always play BG1 vanilla, and the ONLY fix I apply is the elven racial trait fix. Don't fall for the fallacy that the popular fix packs don't change or add anything; they absolutely do, and drastically if you are the kind of person who says 'yes' to all the prompts. Even with the latest fix packs, there are still bugs, but that goes for any game.

Want to play vanilla? Do it. I do.

All the links and information you should need are in the sticky threads I mentioned.

Playing the games vanilla works very well.

I am purist and I always play vanilla (unmodded) BG1 and BG2. I completed both many times and have never encountered any bugs (except for accidently triggering a potion exploit once). So go no worries about it, you can play them as they were released.

It's more than possible.

BG has an extensive collection of mods, fixes and tweaks that add content and conveniences and graphical improvements, etc. - you can even turn the series into one seamless game - but vanilla BG is solid and more than playable.

For instance, I wonder how I ever managed to play without stacks of ammo larger than 20, but it's not that big a deal.

Mods work great to make your own custom experience and to extend the life of the game with additional content or make it look/run nicer for modern sensibilities- or to add convenience features to make your life easier. But the vanilla experience is solid. What few bugs and glitches exist are non-intrusive and you'll be hard pressed to encounter any.

There are plenty of BG purists who scoff at mods and insist vanilla is the only way to play.

On a side note, I'm eternally impressed at just how simple and efficient BG mods are to integrate and use. The technically challenged such as myself thank the BG modding community profusely for their accessibility. The user experience really is wiz. It's also neat how they've worked really hard to make sure mods conflict as little as possible and are compatible with each other. I'm not usually in the business of modding games extensively because I lack both the time and the patience to screw around with it, but modding BG is all sorts of easy.

Thanks for some great answers - the reason I ask is that I am for the first time in my life playing Fallout 1+2, and modding Fallout 1 was just excruciating pain, so many things went wrong.

Now I'll move onto the BG-series soon, and I can't tell you guys how excited I am about playing THEM for the first time too, me being a big RPG-fan who loves games like Planescape Torment, Final Fantasy etcetera.

I'll either play vanilla or install what this guy says:

https://www.gog.com/forum/baldurs_gate_series/newbie_guide_modding_bg1_if_you_buy_bg1_bg2_from_gog/page1

I actually beat BG1 Vanilla recently. I realized that I never actually played Durlag's Tower back in the day. So I'm going along enjoying the rush of memories step by step, and then I stumble across an area which is bizarrely, unnervingly new!

So yeah, very playable. I didn't encounter any noticeable bugs.

edit: deleted because my comprehension skills suddenly abandoned me >.>

If I could, I would buy back my Baldur's Gate virginity. Ten-fold.

Count me as +1 for the "Play BG the vanilla way" vote. I too had no noticeable bugs. Play it the way the original designers originally intended it to be played!

After several play-throughs, use mods if you need to spice it up. But until that happens, definitely go vanilla.

I'm a vanilla man too. Mods screwed up things for me. And I like playing it vanilla for the historical reasons too. I like playibg it the way it was left.

Thanks said, I picked up ee and will eventually play that. I have enjoyed the iwd ee. It introduced some bugs I didn't remember, though (but my memory on that game was very hazy)

Ditto with the first part of your post. I had BGT and must have installed it wrong, because when I got to the end of ToB it kept crashing. I think BG1 in general hasn't aged too well, but I developed an appreciation for it.

Edit: grammar

It is possible to play BG1+2 vanilla on a modern machine (see below). There aren't too many bugs.

I might be done with the EE versions now. I started the Vanilla version of BG1 with TotSC a couple of weeks ago, to get back to the game in a state that is closer to how the developers intended it be, and EE seems over-the-top. Installed on my Windows 8.1 laptop and no problems yet. I am about 1/3 through. I did install some patches/fixes/minor mods thus:

*Install Baldur's Gate (BG1) (can buy the DVD's on Amazon.com, or original CD-ROM's from E-bay.com)
*Install Tales of the Sword Coast
*Install Tales of the Sword Coast patch BGTalesUS5512.exe from sorcerers.net/Games/BG/index_misc.php
*Install BG1FixPack11.exe from baldurdash.org/BG1/bg1fixes.html
Optional: test to see if the game runs without problems (my system is Windows 8.1 - has no problem to run BG1 vanilla)

*Optional: now install BG1 Unfinished Business from pocketplane.net: installed all except for Permanent Corpses; Flaming Fist Mercenary Reinforcements

*Optional: now install Baldur's Gate Mini Quests and Encounters v13 from Gibberlings3.net: installed all

*Then install bg1tweaks-v5.exe from Gibberlings3.net; these conveniences were installed:
*cosmetic changes such as remove helmets
*max hp on level-up and for all creatures
*100% spell learning and no cap
*ammo stacking to 40 only; no other increased stacking or no bags of holding or such

*Lastly install Widescreen from gibberlings3.net/widescreen/ Extract to game folder, run SETUP-WIDESCREEN.exe; set to 800x600, yes to update saves
*Install BG1 interface improvement from athkatla.cob-bg.pl/viewtopic.php?t=3257 Extract to game folder, run Setup-TWM_GUI.exe

Looks very nice at 800x600. There are still a few possible bugs on minor quests where the number of foes has to be counted, such as the Half-Ogres for Bjornin. But, these are just minor quests so actually just take it in stride if a minor quest does not finalize properly. Use Sword Coast Keeper only if you *really* have to finalize all the minor quests as well.