Keeping a backup of your most important files is an absolute necessity these days. An external harddrive is an option. A small, keyring jumpdrive is another option. But, what is your were in an absolute disaster? One like Katrina?
One option is Yahoo Briefcase. If you have a Yahoo ID, you have a Yahoo Briefcase. Sign into your Yahoo email account, go to the Yahoo main page, then to ..all Y! Services, the select Briefcase. You can upload your most important files there. You'll have about 30meg of storage to use.
The main option, for the normal user and even power users, is Streamload. Streamload is an online storage site. You can store up to 10gig of files! That what I said: Ten gigabites! For Free!! And I'm all about free stuff. You can purchase more storage for a monthly price, as you can with Yahoo Briefcase. With the free account, you're limited to 100meg of uploads a month. Paid accounts get more upload limitations.
If a major hurricane hit's me, and I lose everything, I'll lose my hardware, but my most important files will be availabe as soon as I can get to a computer hooked to the internet.
My suggestion: Use your laptop or desktop store your programs, and maybe that huge music collection you downloaded. Keep your current files on a jumpdrive, and all your important files on online storage. When you have a major computer crash, you'll just shrug off the inconvenience, but not be devastated.