quake 3 ran dark for me as well, turning up the brightness and the game was getting a bit washed out in colors.
AMD Athlon XP 1700+
ECS k7s5a v1.0
256 mb PC2100 ddr
Abit Siluro Geforce 4 ti4200 64mb
Western Digital Caviar 40gb 7200rpm ata100
Windows XP Professional