I have a Frys Intel Celeron 2.67 GHz desktop PC. I want to backup my stuff, and I'd like it to be on a regular basis, automatically. At work we just copy stuff to a flash drive, but I have a friend who bought a Western Digital external drive for backup and likes that. Then I have people tell me that online backup is best because if you have a fire you still have your stuff. Thoughts?
I think you mean that "offsite" backup protects against things like fire, not "online". Even if you don't go to the lengths of keeping your backup "offsite", you should at least keep it "offline" (i.e., on an external device not connected to the computer). That protects it against risks such as viruses, power surges, and theft (assuming you keep it separate from your computer and hidden).
It really doesn't matter what you make your backups on, as long as you at least alternate backups to two different pieces of media (two flash drives, two hard drives, or even one flash drive and one hard drive). If you have your data on at least two different external devices, then you can recover most of your stuff even if one of them fails.
The very best protection is to keep one copy offsite. I do daily incremental and weekly full backups to alternating disks, and once a month I take one of them to my bank to put in my safety deposit box. That protects my data from just about every risk that doesn't kill me too.