Im pretty sure it will run on Vista. I sometimes run my old CS 1.6 games on Vista, for that reason I chose to go to the dual operating systems(xp/VistaHP). It doesnt take much to keep XP on your system. Its not a resource hog, my frame rate suffers by as much as 30 fps when I run my steam games on Vista so I could only deduce it meant it was a good idea to keep xp around if only for that reason. I also keep a seperate logical NTFS system to hold all my Steam game data. As the great band, Offspring said "You gotta keep'em seperated".