Noone could guarantee that all you XP software would run in Vista. However, Vista has two "run as" features. One is run as Adminstrator (you will understand the use of this when you begin using Vista) The other is a "run as" compatibilty mode, which offers Win95. and onward.
I have succesfully installed 39 XP programs in Vista without hiccups. Only one needed the compatibility mode feature. Vista will NOT, as a standalone OS, run any old Dos programs.
If you want a more definitive answer, then try this page. It referes to the RTM 6000 release which is identical to the final release. -compatibility is improving all the time as software writers produce new releases or patches.http://www.iexbeta.com/wiki/index.php/Wind...patibility_List
It might be important for you to also check hardware compatibilty.