clean user.dat and system.1st

Is there a way to clean the contents of user.dat and system.1st?
System.1st is almost 6 meg big. This file and user.dat have a history list in them that show URLs over a year old. I read that one of these can be deleted... the actual file itself can be deleted? I may have also read that another pgm may be dumping its history info into one of these files...I can't remember which or why.
This is not a spyware issue. At another forum a member there sugested AdAware to get these URLs, I knew better but gave Adaware another shot.... no spys found there although there were they existed elswhere.
thanks
Greg

 

User.dat and System.dat together form the Windows 95,98, and ME Registry and you should NOT touch those.

The way to (cautiously!) edit or view the registry is by using the Registry editor: Regedit.

The System.1st file is a backup of the registry created during the final stage of Windows 9x Setup. You shouldn't touch that one either.