On my workstations, I genereally burn important data to CD or DVD on a fiarly regular basis. It’s cheap, fairly fast, and easy. Of course for servers and for bigger, more robust data backups, you should use backup software (like Backup Exec, for example)and archive your data regularly to tape. You can set it up to run unattended at a convenient time. There are different types of backups (full, differential, incremental) that can be utilized to effectively backup while managing time and resources available.
I agree with anna and add I use floppies for address book and favorites and cdrw for QBPro and other long winded programs. Keep all your cd’s and floppy backups as well as your OS and Program disks in one of those FIREPROOF SAFES and keep them in cdenvelopes. A backup is no good if it is destroyed by water or fire or the kids playing.
You are out of buisness if you have NO backups.