Lol, funny posts. Basically if you buy a 8x agp card, and u have a 4x slot, its only gonna run at 4x. Anyways I looked and I found this, ATI Radeon x1300 pro -- $165. Hope it helps.
LoL no prob i took it as a funny comment nah i dont think so you got planty of RAM and your CPU is gewd if you upgrade with the 7800 GS go with 1 more gig of ram later