I don't know what programs you can't run. Maybe you can illustrate us. I used a Virtualized XP for two programs, a win3.1 table of integrals (that refused to work in any emulated version of windows, later I found a compatible executable), and a DOS program to use with a detector connected to a serial port: the program worked but the serial port emulator didn't. In any case, I prefer Vista over XP because: I can access any of my programs typing the first letters of its name, the search utility is better, the interface is robusts (if a program hangs it doesn't hang the system with it), the security works better (I don't have any antivirus installed, and the only risk situation was made by myself and rapidly contained). I have Vista in 3 machines by now and the OS doesn't hog the system in any of them.