The 6600GT will win out almost all tests, yet on an XP2400+ the performance difference will often be almost nil. ANyway, if it comes down to price, the 128MB 9800 Pro (get a 256-bit one NOT a 128-bit one), is often much cheaper. I paid $170 shipped for a retail BBA, whereas the 6600GT AGP is $225+ now. Sheer Performance goes to the 6600GT, BUT if price matters and you find a R9800 Pro to be $50 cheaper, it will perform almost the same on that XP2400+ system of yours(depending on the game), and IMO be a better buy for you. Priced the same, buy the 6600GT for sure.
EDIT: My only beef with the 6600GT is that it was announced as a $199 card, but the AGP ones are selling for $225-275 instead so far. This "premium" over list price makes me think it is not a best buy whatsoever right now, yet on a higher end system it would be easily justifiable to buy one if a plain 6800 or higher was out of price range. A BFG 6800OC can be often found in the $250-260 range, so make sure you aren't paying too much for the 6600GT that you could find a 6800 for almost the same price.
MSI K8N Neo2 platinum, A64 3000+, 1GB Corsair XMS 4000 Pro Series, Radeon 9800 Pro<P ID="edit"><FONT SIZE=-1><EM>Edited by Pauldh on 11/25/04 11:47 AM.</EM></FONT></P>