Nanotherm PCM+ or Artic Silver Ceramique are excellent choices, both perform very well in recent reveiw comparisons. Also Artic Silver has just released AS5 and from what I gather from peep's doing reviews on the stuff outperforms all current TIM's.
Asus K8V-DX A64 @ 2600mhz w/Promie (limited by BIOS)
2x256mb Corsair XMS3200LL
ATI R9800pro @ 549/832 w/Vapochill
PC Power & Cooling 510w
IC7-G 2.8c @ 3920 280fsb 5:4 1.725v w/Vapochill PE
Corsair XMS3500c2 @ 224mhz 2-3-2-5 2.95v
TI-4600 @ 350/750, SB Audigy, Antec TP55026,006 3Dmark01' ">http://service.futuremark.com/compare?2k1=7105334 <a href='http://service.futuremark.com/compare?2k3=1302231' t