Psyringe
Scout
Definitely XP. Among its other problems (like lack of drivers), Vista is a memory hog, and the amount of free memory is one of the most important factors that influence Civ4's performance.
Actually, I think the best OS for Civ4 is Windows 2000, because Win2000 has an even smaller memory footprint than XP.
Actually, I think the best OS for Civ4 is Windows 2000, because Win2000 has an even smaller memory footprint than XP.