You could buy a geforce 6800 and try to open up the extra pipes, that would be a pretty decent upgrade. I found a 6800 for 145 USD on pricewatch. You could also get a geforce 6200 and mod it into a 6600, but that wouldn't be much of an upgrade really, however the price of the 6200 is only around 65 dollars. I bought a x800 GT when I upgraded from my 9800 pro, and it was a fairly decent increase in performance when overclocked for around 150 dollars. My girlfriend just bought me a Connect3D x800GTO for 175 dollars with a 25 dollar rebate, which I have every intention of modding into an x800XT. If you bought any of the last two, you would see a sizeable increase in performance, and you would be able to buy a pci-e board and still spend less than what the x850XT would cost you. I guess what I'm trying to say is, if you're going to buy a new video card, you might as well take the hit now and move to pci-e. I really don't see it being worth buying a new, expensive agp card when pci-e is here to stay. I assume you have your reasons though, so I would go with the 6800 and the pipe mod.
