For files that you want deleted permanently that are giving you the "cannot delete file... in use by another program" message, when they are NOT in use by another program:
Let's restart the PC and hit F8 to reach the "Advanced Boot Options" menu.
From this menu choose "Safe Mode w/ Command Prompt", let it boot and log in normally to a local administrator account. Once logged in change directories to the location of the file in question. Once here let's use the "del" command to delete the problem file.
This method prevents the "explorer" shell from starting and "holding on" to the file.
http://www.snapfiles.com/get/Unlocker.html.
After download, I suggest you copy a ahortcut to this file into START->PROGRAMS->STARTUP.
Let me tell you how it works: AFTER starting Unlocker (having the tray wand icon active), try now to delete the file. Don't worry; just click OK and Unlocker will pop up and show you the locking handles. Select them all and click 'Unlock' or just click 'Unlock all'. DONE! Now you can delete the file without problems. No restart, no stress; this is the simplest option. TRY IT, IT'S REALLY GREAT!