I suppose the game files could be corrupted, but apparently the ISO's did work for others. Im using a nvidia 8600gt, and i downloaded the latest drivers for it about a month ago.
I had a similar problem with fallout 2, but deleting one line in the .ini file allowed me to run it.
I'd like to find someone else who uses xp 64 and has Omikron. So far google has failed me.