http://www.theinquirer.net/default.aspx?article=35350although i went for a powercolor x850 pro (12 pipe) and flashed it to a 16 pipeline x850 xt pe
got that off lowestontheweb a month or two back, instructions for flashing and checking if its flashable are on techpowerup.net
although id beware of "fake" x850 pros using substandard ram from the far east, spotted one or two on ebay when i was looking.
compares to a 6800 ultra if your thinking in nvidian.
either that or ebay for a 6800 ultra is my only other reconning.
youd seriously be better off getting a new mobo if that A64 is a socket 939 one and saving the hassle of hunting down an better AGP card than youve currently got.