So after doing much research and testing the software on XP and Vista, I have arrived at my conclusion of what CCleaner is and what it can do for you.
After installing CCleaner, I remembered I had seen it before, at a company I had worked at. Some of the employees were using it to clean up any evidence they were surfing the web. Basically it is software that helps you clean up your online “tracks” and other Office documents, from your computer. It also helps check your Registry to make sure all your applications are running properly. It seems very sophisticated for a small application; it has a lot of functions to undo what you’ve done, in case you delete something serious on accident.
It’s not a virus killer though, or a malware remover. Whoever told you that is mistaken, it has nothing to do with virus removal. It’s the kind of application for either very paranoid people, worrying about people being able to find out what they are doing on the internet, or an OCD person that like to keep their computer as clean as possible. But it’s a good application for keeping your computer clean and optimal.
Here is the link for download, it is free, and they do accept donations as well.
http://www.piriform.com/ccleaner