CCleaner

CCleaner is a system optimization/cleaning tool. It removes unused files from your system, allowing Windows to run faster and freeing up valuable hard disk space. It can also clear your internet history and act as a fully featured registry cleaner. CCleaner is fast (normally taking less than a second to run) and contains NO Spyware or Adware! Portable version: http://www.piriform.com/ccleaner/builds.