I can delete temporary files, cookies and even registry entries from msconfig of my own. What is the other use of registry cleaner so that I get the benefit of purchasing it?

I just bought a PC from ebay. All of the programs are uninstalled, but there are still a lot of registry entries from this long gone programs. Does anyone know of a free program I can use to clean the registry of this clutter? Thanks!!!

7th

It says it will remove unneccesary, files, registry entries and internet clutter from my system to free up disk space.
Will this take away all of my folders and pictures and stories and poems I’ve written and stuff that I have on my desktop? Is this a good thing to do or is almost like rebooting a computer?! HELP!

I have 3079 mb ram memory, am running vista, and still it takes forever to open programs. Just opening a file with thumbnail images takes a good 30 secs to a min. I have run multiple malware scans, anti-virus scans….have cleaned all my temp files and unused registry entries. Why does my computer still run so slow?

I want to start a new live by getting rid of all the malware, useless registry entries and etc, because my system has become very slow.
But windows XP safe command prompt mode gives ‘access denied’ if I try do rename or delete them.