Lots of folks (including me) perform system backups into Zip archives. Over the years I became leery of proprietary formats used by various manufacturers of tape drives, removable disks, etc. Zip files give me a much better feeling, and make it a lot easier to browse through my backups. Martin Aignesberger must feel the same way, because he has created a product that performs daily backups into Zip files. This is a commercial product, but he does offer a 30 day free evaluation.

http://aignes.com/zip.htm