If your staying AGP, your only card is the 3650 which every1 has stated. Personally, with performance gain that you get from switching to closer to this generation hardware, it would justify the extra money paid over all.
If your staying AGP, Ignore the bottom.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------
I would say that for 3.0 max setup would be 280 GTX sli MAX. Anything over 3 cards generally will show a bottleneck at low resolutions at that clock.
Since your LCD is 1280x1024, I would have to say, unless your an enthusiast. That 1 280 GTX would even be over kill.
Do you have any plans of changing monitors?
what games do u play? Crysis makes a computer cry even at that resolution.
I would go with either a 4870 512 or a 260 GTX to have a decent powerful card.
if your going to want to max out games like grand theft auto 4, Even my 3 280s gets around 30 fps even if i lower the resolution to 1280x1024. That might be because of lack of drivers, but sitll.
I wouldn't recommend the 8800 GT because for 50$ more (generally) on newegg, you could grab yourself a 260 GTX sp 192 and it would give quite a boost over the 8800 GT, which is going to be put to rest soon any ways as games are becoming more and more texture heavy, and demand more AA