bit-tech.net posted a review on the GeForce 7800 GS AGP - the fastest AGP
card ever

All in all, the GS is a decent performing card, and will quite possibly be the last bastion of the AGP gamer. We've examined the value of the PCI Express upgrade path, and you'll have to decide if that is for you or not right now, based on the pricing economics. As it is, this is easily the best thing you can add to your ailing AGP system.

BFG 7800 GS OC on AGP Review