Retail licenses (full and upgrade) of Windows 7 are transferable. With an upgrade license, the new computer must also already have a valid license.
Referring to the Windows 7 retail licenses:
2: INSTALLATION AND USE RIGHTS.
a. One Copy per Computer. You may install one copy of the software on
one computer. That computer is the “licensed computer.”
b. Licensed Computer. You may use the software on up to two processors
on the licensed computer at one time. Unless otherwise provided in
these license terms, you may not use the software on any other
c. Number of Users. Unless otherwise provided in these license terms,
only one user may use the software at a time.
d. Alternative Versions. The software may include more than one
version, such as 32-bit and 64-bit. You may install and use only one
version at one time.
To use upgrade software, you must first be licensed for the software
that is eligible for the upgrade. Upon upgrade, this agreement takes
the place of the agreement for the software you upgraded from. After
you upgrade, you may no longer use the software you upgraded from.
17: TRANSFER TO ANOTHER COMPUTER.
a. Software Other than Windows Anytime Upgrade. You may transfer the
software and install it on another computer for your use. That
computer becomes the licensed computer. You may not do so to share
this license between computers.
b. Windows Anytime Upgrade Software. You may transfer the software and
install it on another computer, but only if the license terms of the
software you upgraded from allows you to do so. That computer becomes
the licensed computer. You may not do so to share this license between