Ideal system - money no problem -
Athlon 64 FX53 - Why, it beats the crap outta ANY P4 for gaming.
Mobo - Asus or MSI, why stability.
RAM - Corsair DDR400 TwinX, why, the best out there.
Vid - Toss up, personally I would take the 6800 over ATI latest offering. Why, Shader 3, more 'up to date' than current ATI high end card. Why didn't ATI include shader 3, they didn't know how to lol.
No shader 3 not used yet....but it will be.
Before all the nVidia vs ATI whines - I currently run an ATI 9800, I also use a dual boot XP64 / Win 2k system. The Still 'beta' ATI XP 64 drivers SUX. Yes I know XP 64 is still beta - but it is rock solid!!!!