Athlon XP 2500+
512MB RAM
ATI AIW Radeon 9800 Pro 256MB
Oodles of disk space
I've largely soured on first person shooters. I will check out Doom 3 though. I suspect that it won't get the playing time like GTA3, GTA3:VC did and GTA:SA will.
And speaking of Duke Nukem Forever, what an appropriate title... The only first person shooter that I really liked and the kick ass followup is late, late, LATE!