Well, you could give the 1.04 patch a try first, if you don't mind it.
In the meantime, lemme google for "GLW_StartOpenGL() - could not load OpenGL subsystem" first; that's a common error with quite a few possible causes.
You could give these drivers a shot: http://omegadrivers.net/ati_winxp.php
Before going to that length, try this first: Open the Catalyst control center and browse through the settings. Make sure that acceleration is set to maximum, OpenGL is enabled (if there is any way to disable it, that is; I don't have an ATI so I can't really tell if there's still such an option in the latest driver versions), and if you have multiple displays attached to your video card, deactivate all but one.
And while you're at it, check out the version number of your Catalyst driver suite and post it here.
Next option is to try the fix suggested at the bottom of this thread:
And if that doesn't work, try the Registry fix provided here: