Unless you don't save anything in your computer, you should regularly backup your files. (Look who's talking. Hehe.)
Have you experienced typing a long document (or even a long blog post) and then your PC shut down or hanged up on you? And you didn't save what you're doing?!!! That's a very "shitty" situation. Hahaha. Especially if that's your thesis, presentation or, much worse, the application you're programming. Teehee. ^^
So that's much the same way with backing up your files. You never can tell when your PC will die down on you (read: bluescreen) or your hard drive corrupted (or eaten by red ants) or your PC stolen (knock on wood).
Do you have a regular backup schedule? And if so, where do you store your backups?
Hayz, I still don't have an external hard drive because my friend bought the HDD I was eyeing. So I'm still stuck with CDs/DVDs. And I haven't done my backup since a few months ago. Good thing, I backed up my cellphone's files last night. ^^