Didn't have time to read the whole thread so not sure if this has been said but:

If you wan't a good AGP-based card, either take one based on Nvidias Geforce 7600GT or 7800GS chipset. 7800GS is the best you can get with AGP, but it's quite costly, near 300€ (~300$).

7600 GT in the otherhand doesn't cost too much, while giving a lot better quality and performance than 7600 GS. Price of 7600 GT is usually just 30-50€ more than 7600 GS. And yes, there is 7600 GT out there for the AGP, it's not a mistake. I have one, and boy does it rock.

All in all, regarding RTW, my old Geforce 6600 GT was more than enough to play on huge units, had to just scale the details.

So, if you have AGP, GET THE 7600GT. Or 7800GS, if you can handle the price.