Originally Posted by low strife
Then get more RAM, because Vista 64-bit is way better than XP's 64-bit variant.
100% agreed. Vista is NOT a resource hog (like the media has made it out to be). It actually puts your resources to good use. RAM is faster than hard drive swap files, hence why Vista uses more of your RAM. Usually 2GB of RAM is enough these days even for Vista. However if you're doing some heavy 3D work, I'd suggest you go 4GB....since that's what you're asking anyway. Go 4GB of RAM and Vista x64. You'll be happy with it. If you've never used Vista before, it takes a LITTLE bit of getting used to. But for the most part everything's pretty much in the same spots as XP.
I for one, suggest you make the switch. Windows XP 64bit is absolutely HORRIBLE. There are a SELECT FEW people who don't have any problems with it. But about 99% of people who have tried XP 64, they hate it. Lack of driver support for the main thing.