CCleaner
CCleaner is a tool for system optimization and privacy that all Windows users should have.
Among its virtues, is able to clean the following:
* Internet Explorer. The temporary files, URL history, cookies, autocomplete form history and index.dat file.
* Firefox. The temporary files, URL history, cookies, download history.
* Opera. The temporary files, URL history and cookies.
* Windows. The Recycle Bin, Recent Documents list, temporary files and log files of the system.
* Windows registry. It has advanced features to remove unused and old entries, including File Extensions, ActiveX controls, ClassIDs, ProgIDs, Uninstallers, Shared DLLs, Fonts, Help files, application paths, icons, invalid shortcuts ... and all with the possibility of reversed.
* Application number. It is able to delete temporary files and recent playlists (MRUs) from many applications like Media Player, eMule, Kazaa, Google Toolbar, Netscape, MS Office, Nero, Adobe Acrobat, WinRAR, WinAce or WinZip and others.
Also CCleaner is a freeware tool and translated into 35 different languages, including Castilian.
Download here