You are allowed to make a 'back-up' copy of your OS. The problem lies in getting it off your HDD. Its actually hidden in a small partition and I have read other posts where the user has made a copy. Unfortunately I just can't remember the process , this site may help ( although it is for XP but I guess the process is the same) How to Create a Bootable Windows XP Setup CD/DVD from a Pre-loaded/Preinstalled Windows System (howtohaven.com)

Another site refering to your problem is here (scroll down to find the entry)
[SOLVED] Removing Vista, but backing it up... [Archive] - Ubuntu Forums

In the above link they talk of something in your startup menu which will allow you to make a backup disk. Anyhow I hope from all this you can find the info' you need. Good luck.

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