What Microsoft says the EULA says, and what it can enforce,
and what the wordl's courts might say, and what it is willing to
try to enforce given the power of public opinion around the world
are four different things.  Some of the more retentive MVPs here
argue that making a clone of an installed OS is a sin.  But none
of them even imply that you're in any legal, financial, or reputational
danger if you do make clones of your installed OS.  But they do
imply that you should feel the dark weight of guilt for doing so.
<hee, hee>
    It should be admitted, though, that one can get additional function
out of a server app if one runs multiple copies of it as virtual machines
on the host computer rather than just one copy on the real metal.

    The common wisdom is that after 4 months have elapsed since
the OS was last registered, the registration ages off MS's database,
and another registration of the same copy of the OS will go unchallenged.
If it is challenged, a quick phone call to Microsoft telling them how your
old PC died and went back to China will have the new installation
registered again without any hassle.

*TimDaniels*