I am still a Socket 939 holdout, but I did just go from AGP x800XTPE to a ASUS a8r32-mvp deluxe with dual sapphire x1950pro's in CF. AGP is just entirely too expensive just justify it's existence any longer, IMO. the same card in PCI-E will cost loss, and that's a bummer, but AGP is going the way of the Dodo...time to move on. Or, you could hold out until ATI releases their new cards...or give it 6 months until both camps release mid-range cards, and make your decision then. If you're still on Socket 754 though, it's really time to bite the bullet.
You're probably better off waiting at this point. If you can save up $450-$500 dollars you'l be able to switch to a decent pci express system that'll be alot faster than you current one. (Opty 165 - $155, AM2 mb - $80, 7600GT - $125, 1gb RAM - $125)