There is loads of software you cab get to back up your system for you.
Have a look at this list click here
Some is shareware and sone free. I use SynBackSE (the shareware version) but there is a free version with a more limited functionality.
One thing to decide is whether you want to backup an image of your whole system disc so you can recover the system back to a known point and/or backup system files that you can recover any file individually. You'll find both types available in the list.