Windows 7 and Windows XP are basically the same thing, Windows VISTA had a different kernal than XP but because it was so unstable they decided to keep the graphics and run it with Win XP kernal, so basically Win 7 = newer version of Win XP. Only problem is that there are some programs that do not run correctly on Win 7 like on Win XP but that doesn't change anything you just have to run it in compatability mode with XP and boom should work or atleast 7/10 times it does anyway, if not there should be a program that will let you. But because I have more experience with XP than 7 I would choose XP because of how much I know of that OS. Overall: Win 7 for better performance and Win XP for capabilities and long time using it for exp. Preffered: Linux systems!