Ive been looking to upgrade aswell but I came to the conclusion that I wouldnt upgrade at present... waiting a few weeks and doing motherboard and gfx

Couple of things to bear in mind.

1. the very impressive Nvidia Doom3 bench marks were based on there PCiexpress cards which arent even on the shelves yet I currently have an ATI 9800 pro and can run Doom 3 perfectly at 1024 x 768 medium settings which is probably the max for your current proccesor anyway.

2. 16 x PCIexpress is away to hit, the bulk of future motherboards wont have AGP so if you spend £300 - £400 on an top end AGP card it may not be any use when you upgrade your PC next.