CPU Help

[jpk]

I just bought a ASRock 939 Dual SATA2 mobo and need suggestions about what cpu to get for it. Currently I have a Abit NF7 rev2 with an Athlon 2800+. 1 gig of Corsair PC2700 ram running dual channel. I got this mobo because I have a 6600GT agp vid card and don't want to upgrade to pcie for a bit yet and this board will allow me to do that. Of course I want the best bang for the buck so what cpu will do that for me? Suggestions? Thanks for your help.