I went from a 9700 Pro to 6800GT an an AXP@2.3GHz which should be a similar sort of upgrade. Posted some numbers: http://discussions.hardwarecentral.c...ghlight=6800gt
The 6800GS AGP is great because it can be unlocked and overclocked to beyond 6800 Ultra spec. 7800GS doesn't make as much sense IMHO because for £200 you can buy a new PCIe mobo and a decent graphics card.
Opteron email@example.comGHz (stock HS/fan), Asus A8N-SLI SE (passive NB), 1.5GB RAM (2:3:2:5, 2T), WD Raptor 740GD 74GB, Maxtor DM10 300GB, Asus EN7600GT SILENT@???, M-Audio Revo 7.1, Nebula DigiTV, Dell 2005FPW, Enermax 431W Active.