Disclaimer: I'm not a lawyer!
You may want to read the EULA, especially Section 18:
18. TRANSFER TO A THIRD PARTY.
a. Software Other Than Windows Anytime Upgrade. The first user of the software may make
a one time transfer of the software and this agreement, by transferring the original media, the
certificate of authenticity, the product key and the proof of purchase directly to a third party. The
first user must remove the software before transferring it separately from the computer. The first
user may not retain any copies of the software.
b. Windows Anytime Upgrade Software. You may transfer the software directly to a third party
only with the licensed computer. You may not keep any copies of the software or any earlier
c. Other Requirements. Before any permitted transfer, the other party must agree that this
agreement applies to the transfer and use of the software.