I think I may have figured some of it out.
After reinstalling the Cat 3.1's and the new ATI Control Panel as well, the performance has almost doubled.
Before, even if i set the D3D and OpenGl bars over to Maximum Performance, they didn't seem to make any difference, but after installing the new version Control Panel and wiping the one that came on the Hercules Install CD, doing the same thing almost doubles my 3dMark and my frame rates in UT2K3.
I still have the problem with the original Unreal Tournament in that it will run in OpenGl but has lighting problems and lower framerates than on my GF3, but if i try and change the renderer to D3D, the game crashes with a critical error 'Failed blt: DD_OK'
I think my best bet here is to try a reinstall and see if that allows me to use D3D, and if the framerates improve over the opengl ones.
AMD Athlon XP 1900+
Abit KR7A - Raid
2 x 120Gb HD and 1 x 20Gb HD
512Mb DDR 2100
SB Audigy 2 Platinum
21" Iiyama & 17" Hercules 920 DVI
Hercules Radeon 9700 Pro