The Program Compatibility Assistant detects known compatibility issues in older programs. After you have run an older program in this version of Windows, it notifies you if there is a problem and offers to fix it the next time you run the program. If the compatibility issue is serious, the Program Compatibility Assistant might warn you or block the program from running. If that happens, you'll have the option to check online for possible solutions.
To find out if your programs (or programs you plan to buy) are compatible with Windows Vista, go online to the Windows Vista Compatibility Center. This website contains a comprehensive list of programs and devices that work with Windows Vista.