Which Version of Vista? And rig help!

OK, so i can build a $1400 rig, here is the specs
THis is my first rig im building from the bottom up.

Asus nForce 680i SLI Mobo
Apevia X-alien case /w 500 watt power
Intel Core 2 Duo E6600 ( Might get lower one for price. Saves 40$ for like .27 GHz)
2GB DDR2 800
EVGA Geforce 8800GTS 640MB
WD 150GB 10,000RPM
WD320GB 7,200RPM
Sony CD/DVD Burner

1313$ for all that, (not including 60$ mail in rebate, and 30$ shipping)just need a OS.
I decided that Vista cant slow me down that much, and once good drivers come out and SP ( which i dont have to pay for right?) that it will improve.
The final question is... which VISTA?!?!?!
I am a gamer, not like running a business o anything.
Do i need vista ultimate?
Home Premium
etc.

And 64-bit or 32-bit.

Im not ordering this all now, (Probably nottill Nov.)so hopefully the price will drop, if u have any suggestions on changes i should make, plz say so. I really need cheaper changes.

Thanks, thats a ton of help, I decided to cut dow my 8800 GTS to 320MB, shaving off 100$. Cause im still using 19" screens.

Then i could cut down the processor, and get a better power and case.
I dont really are about sound, but then again.i never have experienced anything beyond headphones and stereo speakers. So i think i can survive with integrated.
Im gonna link to Newegg all this stuff in my next post.