A.
Microsoft has replaced the old "Designed for Windows XP" logo program with a new logo program. "Works with Windows Vista" shows that the software or hardware has been tested by the manufacturer to ensure compatibility with Vista. "Certified for Windows Vista" shows that the software or hardware has been tested to meet all of the technical requirements to deliver a superior end-user experience.
Additionally, PC's may carry a "Windows Vista Capable" sticker, which means it's suited to run Windows Vista Home Basic edition, whereas PC's with a "Windows Vista Premium Ready" sticker can run all the versions of Vista up to Ultimate Edition.