Ah-ha! quad core! see if intel has released any patch for XP for quad core. It did for my core 2 duo, and the game was more stable after that. Check that in microsoft's website. its not available via windows update, or even on the web update. you have to search and install it manually. its for all applications on windows xp, not just bioshock , so dont search for "bioshock" on M$ site lol.