Choppy w/Radeon 8500

[Neil Gower]

I'm trying to run ut2003 on a RH7.2 machine, Athlon XP 1800+, 512MB DDR,
Radeon 8500 128M.  I've installed all of the latest patches (2166) via
the updater.  Trouble is, even if I crank everything way down (640x480,
lowest settings or disabled for all details, etc, although resolution
doesn't seem to matter), the game often gets choppy.  It's especially
noticably on DM-Antalus, whenever the big white spikes in the center of
the map are on screen.

I'm using ATI's latest linux drivers, v2.5.1.  Other games work fine,
like UT and Quake 3, and I know my libGL is hardware accelerated,
because Heavy Gear 2 won't even start if it's not.  I looked through
/var/log/XFree86.0.log and didn't notice any errors or other weirdness.
I'm using the latest stock RH7.2 kernel, "2.4.18-19.7.x".

Thoughts or advice?  Is my machine fast enough to expect smooth gameplay
on maps like DM-Antalus?  Any help is greatly appreciated.

Cheers,

Neil.