Windows Vista has a new more attractive Start Menu button that no longer requires you to scroll through the cascading "All Programs" view. Even the word "Start", that has been part of the Start Menu button since Windows 95 days, is now replaced with a Windows Vista's blue Orb logo.
Windows XP users can also add a Vista style menu on their desktop using the free Vista Start Menu Emulator, a standalone program that has the same look-n-feel and some common features as the default Vista Start button.
Vista Start Menu Emulator won't replace you existing XP Start Menu but place a Vista style wheel atop your Start Button. Or you can drag the Vista wheel on the right side of the task bar and have access to both menu styles.
Vista Start Menu Emulator Requires .Net framework 2.0 [via etc]