In today's Fry's circular they're offering a Radeon 9800 Pro 128MB DDR 8x card for $189. The price isn't amazing but it's not too bad either. I currently have a Geforce4 4600ti in my 2.6ghz 800mhz FSB 1gig of ram machine.
I have had a hell of a time finding benchmark comparisons between the 9800 Pro and the 4600ti. From what I can tell, the 4600ti "compares" to the Radeon 9700, and the 9800 is a better, faster card than the 9700.
I'm willing to spend the $200ish to upgrade, but am curious if that's a decent upgrade. I'm not necessarily loyal to either nVidia or ATI. I use the machine mostly for newer games, and am currently playing Far Cry, Battlefield Vietnam, X2, Prince of Persia, etc. The 4600ti runs these games pretty well, but the card is now over 18 months old now and I'd like to upgrade without spending hundreds on the latest and greatest.