Back up system on web

You can use Windows Live SkyDrive (http://skydrive.live.com) for your online storage needs. It's free and its 5GB worth of files that you can store. You have the option to set your file as private or for public sharing as well. All you need is to use your Windows Live ID (or if you don't have one, you can create that for free). You can also try to use SnapDrive (http://www.snapdrive.net), though this one is only for 2GB worth of space. I'm sure there are a lot of other free online storage options for you (including your own email account).

I do this with Norton 360 virus scanner - when you purchase it, it gives you a bit of online storage and you can also purchase more. If you don't want to save everything online though - I would suggest looking into getting an external hard drive. You can pick them up at computer stores everywhere, or online at amazon.com even. With a 200gb or so external hard drive, you probably wouldn't run out of space any time soon, and you could just plug it into your USB port on your computer whenever you wanted to access anything you need on it.