Begin by downloading a nifty little program www.winpatrol.com
This will help you to identify quickly which programs you don't need as for
instance: You don't need media players until you actually have a need.
Disable Windows Media Player, Real player or Dell Player. If you don't
dabble in photos regularly, disable Roxio, Windows Photo or Picasa if
loaded. If you don't play games,then disable all the games.
Take your time, go slow (THINK) and keep notes about what you have changed.
Remember that setting up a new computer in Vista might take a couple of
weeks until you get everything organized the way you want it.