As an aside, I don't actually think it's unfair for MS to block access to Windows to users who are using illegal copies of Windows. It's their product; it stays their property so long as you haven't pay for it. If you don't like that, use something else instead (like Linux for example) or pay for the license.
Please note I'm not accusing you in particular of using an illegal copy of Windows. I'm just expressing surprise at people getting outraged when their PCs stop booting up into Windows because they have invalid licences (there was a story in China recently, which as I remember it was reported with glee by one of the Mac sites.)
(PS you could always load up the hard disk on another machine and copy the data from there)