The antec 900 is a nice case, the only is the front two 120 mm fans are pretty bright. thinkin bout getting two more and trading those out as it stays in the room i sleep in. also i think putting a fan controller on the case would be nice too as you can control the fan speeds but you can only do it from inside the case. keeps everything really cool no matter how much i have things OC'd inside. the only thing i had problem with was cable management as some things were VERY far from eachother but with a little imagination it all worked out.
Definately go with the 4 gigs of ram, I got 2 gigs of OCZ d9 micron, overclocks from stock 800 to round 1000-1100 without any problems at all just a little up in voltage. would like to have 2 more for vista 64. Big time help in editing movies and photos etc. not so much for gaming.
I would ponder getting the 64 bit ultimate if yer gonna go with VISTA. I could tell a difference between the 32 and 64 but thats just me. i mean hell yer already spending 1600 whats another 100?
Go with EVGA for the video card and stick with the GT. save money and you wont notice a performance difference. plus you can upgrade with there program for just the difference in price when they release the 9 series.
Don't know much bout intel as i use ASUS crosshair with a amd 6000 ocd 3.3 and stable. got that board for the upgrade to am2+ when they get all the kinks worked out after the first gen quad chips. I do know quad over dual is not that great YET just because programmers haven't started writing for 4 cores as they just started writing for 2 cores ie Gal CIv 2 and SupCom etc. so thats just up to you on how much you want to spend.
Looks like a system to be jealous of though for sure....beats mine out