Ccleaner (Formerly Crap Cleaner) is a system optimization tool and is very good and best of all free!

It wipes temporary internet files, cookies, system temp files, and temp application data and MRU lists etc.

Be careful when you run it as by default it will empty the recycle bin and so if you have stuff you want to restore (Not that it should be in the bin in which case) but some do, you won't be able to!

It also has a registry cleaner in there, I would be very careful using registry cleaner if your not sure what you are doing or you could end up doing more harm than good!

Also as you have found out alot of things are NOT free, they rope you in by advertising such and do a scan but when you try and rectify the found problems you will be asked to buy a license, the things found may not be true anyway!

Martin