Best free backup software?

Looking for something that will backup files as-is, i.e. don't store them in some proprietary backup format.

Need to backup regular image files, in addition to locked Outlook .pst files.

I used GFI Backup ( http://www.gfi.com/backup-hm ) for a while, but I uninstalled it after it suddenly stopped working, for no apparent reason. I've previously used HandyBackup (a simple shareware program) under Win XP, but I'm now looking for something else.

Any suggestions?

Thanks,
Jarle