Win2000 Backup Program

I have set a scheduled backup (normal backup) to a company’s server of a few machines my docs folders. It rewrites over the top daily. However it has grown from 1 gig of info being backed up to a backup file 0f 9 gigs in just a month. I need a backup solution for this company. Why doesn’t this work? I am also having trouble restoring anything from the 9 gig backup file. I couldn’t find anything from microsoft on this problem. I need a scheduled backup for this company. Any suggestions?