Thank you all for your answers, I really appreciate your help.
ElMo, that's quite an amazing rig you've got there, although I can't help but think you should've gone with quad-fire, especially with Catalyst 10.7+ offering extremely improved quad-fire support.
Gamerk, that's what I've been doing for about a year now, but recently I've noticed some ArmA 2 players strongly recommending others to disable hyperthreading, and that's a game I've had some performance issues with.
Hey, as long as there's no harm involved, I'm game for trying, so I'm off to the BIOS to disable it right now! Thanks again.