After installing ATI Radeon Catalyst 10.5 & 10.6 the OpenGL subsystem is messed up. Old games such as Jedi Outcast, Jedi Academy, RTCW, Quake III -- really, any game based on the venerable & ubiquitous Quake III engine -- doesn't work. It's not a game problem but an ATI driver problem (you should see the look of *shock* on my face....).

Obtain the atioglxx.dll file from a previous version such as 10.4.
1. download the appropriate 10.4 install package (32 bit, 64 bit)
2. launch install application
3. <cancel> install process. We only wanted to unpack the files.
4. open a command prompt (type "cmd" at the run box)
5. browse to folder containing atioglxx.dl_ (yes, that's an underscore). Mine was in this path:
C:\ATI\Support\10-4_vista64_win7_64_dd_ccc_wdm_enu\Packages\Drivers\ Display\W76A_INF\B_98282
5. expand the file by typing without the quotes (meh, or even with the quotes lol) "expand atioglxx.dl_ atioglxx.dll"
6. copy that newly extrapolated .dll to
a. 64 bit Windows -- c:\windows\system32 and c:\windows\syswow64. I opted to rename my old ones to *.old but I don't know if that was necessary. Also, these old OpenGL games on my Vista 64 bit OS didn't start working correctly until the file was in the C:\windows\syswow64 folder so I don't know the circumstances where it will look in the system32 folder.
b. 32 bit Windows -- C:\windows\system32

Just posted this for posterity.