You need to be pretty clever to break Windows Video DRM. Having worked with DRM for the last couple of years, unless you find the right cracking software, I would bother with the hassle.
Obviously by breaking the DRM, you are also breaking the law!
You register you iPod serial number with your PC, not iTunes.
If you upload (copy) tracks from your friends PC they will work without a problem as long as he ripped them from a CD and not bought them from the iTunes music store.
If he has bought them from the Itunes store you will still be...