Ok these are old but here are two images of max ansio on R8500. They were taken on a fresh install of drivers back in early Dec of LAST year.
Sorry I dont have any thing newer on-line.
I own both the 8500 and GF4 Ti4200. Both are pretty good cards and both perfrom well. I have had no issues with either. Some things the GF4 is faster at, other things (like JK2 and RtCW) the 8500 eeks a touch a head. However the 8500 can not to tri-linear which depending on the game can lead to noticable mip-map lines. The 8500 also has an issue when things are rotated a 45 degrees on the Z axis. Due to a hardware bug it does not apply aniso. I have a SS shot of that:
For FPS this is the only room that I have ever saw this issue! For flight sims this would be a huge problem.
In all I can not recomend either to be much better than the other. If I would have to pick only one....then I would probably go for the GF4 Ti4200 just due that is has bit more speed in UT2003.