Doh! I also swapped out the rest of the machine. (Here is a little tip - drives can do real funny things when they go bad. I swapped everything out item by item before I found out that my old wd drive would lose its mind and completely hose my system.) I need to update my rig.
Currently I have the 4200, a amd 1800, a abit nforce based board with highpoint raid, two maxtor drives on that raid and 512mb of ddr.
The 8500 did Return to Castle Wolfenstein at around 60 fps. (At my settings. 1280x1024x32) The 4200 does it (with the 1800 vs the 1600) around 75. Over clocked I get in the 80s.
The 4200 has a lot of visual artifacts compared to the 8500. In general everything runs on the 4200. The 8500 could be an adventure to get things to run. Everything looked better on the 8500 tho.
I need nvidia to come out with their nv30 so the price on the 9700 will drop to something I'm willing to pay.