How often do you backup your computer?

The entire thing? I would say more then most, but not a whole lot...
Indivual things tho, like Flash or word documents? Every time I by-chance even THINK of the word save.

--EDIT--
Yay just 10 posts till full member! I gotta make um good ones!

Honestly, the only times I back up is with the threat of a format..

I am long overdue..

Every time I get into the jeep to go to work...

Er... Whoops wrong back up...

But seriously, It's been a while, I normally just back up certain things to DVD when I get around 4 gigs (or a multiple thereof).

But I've been looking to get an external harddrive to help with this so I can back up some stuff faster and easier.

I tend to back up my most important files alot so I can take them to school with me or to a friends's house, ie; sprites, music and games.