Well I have heard both sides, here is my experience on both machines, and both machines have Vista Ultimate Edition with Avast Antivirus and they are both 64bit edition .
F.E.A.R.= Runs fine, except when Punk Buster is enabled. I have tried several different ways to get a round this, haven't found out how yet. I give the graphics and game play an 8 out of 10, I'll 2 more when punkbuster is fixed.
Battlefield 2 & 2142= Runs fine, again Punk Buster has issues.
Halo PC: runs perfect, got a few crashes but I updated with new Nvidia Vidoe Drivers, no problems since.
Counter Strike= Runs perfect
My system specs:
Dell XPS 710
Q6700 Quad Core 2.66GHz
2x 160gig SATA Seagate HDD's (No Raid)
8800GTX 768MB Ram
Creative X-Fi Gamer Edition
Crap Intel Board, lol. (Oh well it's a Dell
and I did not have to buy it, it was a gift from my boss)
My other system Specs:
AMD64 x2 4800+ Zalman 9500 Heat pipe
2gig PC3200 Corsair XMS Memory
2x 36gig WD Raptors Raid 0
2x 320 Seagates in Raid 0
Creative Audio X-Fi Platinum Edition
ASUS A8N-SLI Premium Motherboard
XFX 8800GTS 640MB Graphics Card
PC Power & Cooling 750watt PSU