I recently replaced my motherboard, which I use on a dual-boot of Windows XP Professional and Windows XP MCE 2005. The two installations required iTunes to be authorised for each, and I didn't think to deauthorise the computer prior to swapping out the motherboard (which I have now sold to someone at work) and so in total I used up 4 authorisations, which with the one on my laptop left none for my Quantex PC.
So, I sent an e-mail to iTunes customer service asking if all PCs could be deauthorised - and just a day later it was done. I was concerned about DRM but it doesn't seem to be a problem if you use iTunes as the customer service is so good.
Thinking different doesn't seem to that bad afterall.
glad to see that it worked out for you! I personally get rid of the DRM as soon as I buy, that way I can burn everything to a mp3 cd for backup.