Ram on Windows 7 Ultimate 64-bit

Hi I have Win Xp and thought of upgrading to Windows 7.
My Specs are:
CPU: AMD Anthlon II X4 630 2.8GHz
RAM: 2GB DDR3 1666
PSU: OCZ 600 Watt
GPU: XFX ATI Radeon HD 5770
MB: ASUS M4A79XTD EVO
HDD: 500GB
DO you think I would run Windows 7 ultimate 64-bit fine. Like will it really make a difference between 4gig?
The games I to play on WIndows 7 is GTA 4, Bad Company 2, and Starcraft 2.
I played these games all max on WIndows XP.
And how much slower would it be in like overall things on the computer with the 2GB ram than the 4GB ram?

You'd be fine on 2GB of ram. You would be slightly better off with 4GB of ram, but how much of a difference and if it matters - you'll only know for sure by using it.

But 2GB of ram is not a crippling amount on Windows7.

Hell iv'e installed win 7 on several rigs that only have 512 like older dells and they run great with no probs.

If you have a halfway decent flash drive (512MB or bigger), you can use the ready boost feature. It does seem to make a difference...

My Intel E2200 based media box, uses Windows 7 and 2gigs of RAM. It runs just fine. Sometimes it gets a little sluggish, but nothing annoyingly slow. (Mostly when I open up 720p HD videos. Once it gets going, it's fine.)

Now some games might suffer a little, not having enough RAM. Windows itself will run just fine. I would install and check it out. If you think more RAM is needed. Then add more. See if it fits your needs at first..

More RAM will help a bunch, but Windows 7 is not to shabby at managing with a little bit and working with what you give it.

2GB of ram is plenty. Just threw together a media center comp, and although it can't even handle 720p YouTube (Celeron holding me back there), it can play 1080p WMVs with 1GB of RAM no problem.

My i7 has 2GB of RAM, and takes everything i throw at it. I've installed 7 on several computers that only have 512MB of RAM, and they run just fine (with Aero enabled and everything)... one computer is actually using 256MB. Can't use it for more than web browsing, but it works.