Just installed the tenebrae mod http://tenebrae.sourceforge.net/
and this thing is pretty kick A$$.
Seriously, I am impressed and it really makes me feel like I did when I first palyed quake with my Monster Voodoo and thought it was the stuff!
It's the same kinda feel.
If you haven't checked it out, it's well worth it. You'll dig it. (it'll bring your system to it's knees!)