Euhm, what do you mean? You can run programs in compatibility mode by right clicking them and go to propperties, there should be such an option to do that if that's what you mean.
Really depends on what program you are refering to, so let us know what your wories are and we can all help you. But you can select to run any problem in a compatable mode, windows = 95,98,xp,2000, NT and vista..