I have stated in the Vista Thread. Start>Run>msconfig>boot and startup tab.-All startup programs are disabled.
-Why defrag? The installation of Vista is 3 days old.
-The above applies to virus and spyware too.
You would be surprized how many apps really do ahve things loading at boot. WMP, Zune, Adobe, Steam and many more have background processes that load up.
Plus you should defrag becuase even being a fresh install doesnt mean teh files are kept in a nice neat order. They are still spread far and wide across the hard drive upon install. One of the bad sides of Windows.