What would be the best graphics card I can buy for a stock Dell that i bought in 2001?

I think the Dell came w/ an ATI Rage 32mb card at first, which I promptly swapped for an ATI Radeon 9800Pro. I am wondering if my computer could handle an old GPU, maybe an Nvidia 6800 256mb series one...What would be the best graphics card I can buy for a stock Dell that i bought in 2001?The limitation would be the interface in this case AGP but yes you should be able to use a NVIDIA 6800 256mbWhat would be the best graphics card I can buy for a stock Dell that i bought in 2001?Graphics tutorials-http://expertrating.net/