Well I think that settles it! I read the article and I think I'm gonna try 64 bit!

It was very helpful and informative.
3 Questions
1.) Does Windows Vista Ultimate come with the ability to choose between 32 and 64? I'm guessing no when I check newegg and certain places and they're offering 2 versions, but I thought I'd double check here.
2.) What kind of performance gain have you guys had (or others that you know) using x64 with games, browsing, etc. A 25% increase? Or maybe even 50%?
3.) Should I upgrade to 8 gigs of RAM if I use x64? (I'm using 4 gigs at 800mhz currently).