Your best computer backup system is a hybrid using # 3. Scheduled Daily NTbackup.exe Hard Disk Backups and Monthly # 4. Snap Shots using UBCD disk imaging application
There are many methods used to backup your computer data.

1. Commercial services like
Mozy and Carbonite
    pros - easy automated setup  
    cons - initial backup can take weeks, only ONE backup to a single archive. A complete restore could also take weeks

2. Incremental backups to external drives like Maxtor, Seagate or Western Digital
    pros - easy automated setup
    cons - only one backup, a single archive means if corrupted files and backed up and restored

3. Scheduled Daily Hard disk backups - use
NTbackup. one per each day of the week using AT dos command or Windows Scheduling to an External hard disk
    pros - seven complete backups- one per day of the week
    cons - raw / bare hard disks must be handled carefully - static electricity or rough handling can make hard disk inoperable.

4. Snap Shots - using
Ghost, Acronis or Drive Image
    pros - exact copy of your hard disk. FULL recovery is possible
    cons - cannot be done while you work

5. Tape Backup  drives
    pros - can use
NTbackup to save backup to a rotation of 4mm tape
    cons - tape drives are expensive and
4mm tapes have a maximum 40 gigabyte capacity

DVD writer drives  
    pros - inexpensive
    cons - limited 8 gigabyte storage capacity. Easily damaged

As the Dentist says "Only Floss the teeth you want to keep".  Likewise, only backup the computer data you want to keep.