GF4 4200 64mb Doom 3 Players...

This autoexec.cfg file works pretty good for me:

seta image_downSizeLimit "256"
seta image_ignoreHighQuality "1"
seta image_downSizeBumpLimit "256"
seta image_downSizeSpecularLimit "64"
seta image_downSizeBump "1"
seta image_downSizeSpecular "1"
seta image_downSize "1"
seta image_forceDownSize "1"
seta r_useOptimizedShadows "1"
seta r_useTurboShadow "1"
seta g_decals "0"
seta g_showBrass "0"
seta g_muzzleFlash "0"
seta g_showPlayerShadow "0"
seta image_anisotropy "0"
seta image_filter
set r_displayRefresh "75"
set r_brightness 1
set r_gamma 1.3
set com_allowConsole "1"
"GL_LINEAR_MIPMAP_NEAREST"

Nice speedup, 75 Hz, open the console using just the ~ key,
a bit brighter screen.

And add to the desktop Doom 3 shortcut/Properties:

+disconnect

if you want to skip the intro with the 'beating ID Heart'
like :

"C:\Program Files\Doom 3\Doom3.exe" +disconnect

Cheers..

)-()-(