bendy ... you don't need .... or want to backup your entire HDD.
when you use the recovery disc (or f11) it will reinstate your copy of windows in a few minutes .... with clean original windows files
what it won't do is replace your letters, music, videos ... and everything else YOU have created or saved....
that's what you need to backup.
http://www.microsoft.com/protect/yourself/data /what.mspx
google backup PC and look on a few sited ..... be certain BEFORE you do the deed ... 'cause there is no going back if you forget something.
but treat it as a new start ... don't take all the c*ap as well