I’ve noticed that my PC is a little slower than usual. What’s the best free program I can download to clean up unwated files and clear up disk space?

I have to give my laptop back to work. I want to erase EVERYTHING I possibly can. I know how to do the basics with deleting history and cleaning out temp files but I want all of the stuff that is deep in the recesses of the hard drive GONE any help is appreciated! THANKS!

right now i have registry mechanic and windows clean up .. are these programs safe? any better recommendations?

i need something to clean up the computer after i have uninstalled programs…i have a cleaner and defragmenter but i know there should be more free space..i heard there was a free cleaner that was safe to use on windows xp…any ideas……..