Another "Vista or XP" Question

I'm almost done compiling the parts for my new gaming machine, and here's what I have so var:
Gigabyte GA-EX38-DS4
4GB (2x2) Patriot Viper DDR2-800
Wolfdale E8400 3.0 w/ Tuniq Tower
Seagate Barracuda 7200.10 500GB (Hopefully will RAID 0 two of these, depends on price of...)
e-Geforce 9800GTX 512 (When it comes out on April 1st)
PC Power & Cooling 610W Silencer

I'm currently debating between XP 32 and Vista Home Premium 64. I know XP is the solid, reliable player for games and such, but I think it's a waste to buy a 9800GTX and not be able to experience Crysis and other DX10 games in all of their glory. I'm currently undecided, but feel like I might go with XP 32 for now and buy VHP64 when I'm sure that I won't have any compatability issues with my hardware / my games.
Please, convince me.
Thanks for any and all help.

Vista 64!

Crysis works fine on it. I played all the way through no crashes, good frames, though getting high frames on Crysis is tough for any system. Only way to get true DX 10 is vista. There is still a small frame rate advantage for XP but it depends on the system and the game - in some cases Vista is faster. Lot of ppl here and elsewhere on enthusiast sites using Vista 64 and loving it. Lot of complainers who have yet to try it or else tried it right after release who warn you off it. That ought to tell you something.