for the price of buying a new agp 939 (and the cost to maintain upgrade - high end agp = no more wallet) youre better off picking up a used pcie board and saving for a value card. In the long run it's a much better decision.
And dont try the "But i really want to upgrade but its so expensive" speech.
You've waited so long to upgrade. AGP is nearly dead and severely overpriced. Whats a couple of more weeks to save for something better.