One of the most useful tools I use when fixing customers computers is Unlocker
What this tool does is allow you to rename, delete, move and unlock files
that are in use.
What's the big deal about this? Well besides those annoying times when your trying to delete a folder and explorer has it locked for no reason this comes in handy.
But the most useful reason, and the main reason I use it so much is being able to clean up spyware that has infected a system.
When a customer calls me and I need to clean their system sometimes spybot search and destroy doesn't cut it or any other tool. When spyware becomes blocked the spyware makers make a new one, its a tug of war that will never end. So sometimes I have to clean the spyware out manually. Its not to hard sometimes to track down the infected files, but when I find them a lot of the times they are hooked to explorer.exe or another system file and instead of trying to kill explorer and delete by a command prompt I just right click on the file, choose unlocker and delete it!
So for my fellow techs out there, this tool is a must have.