Let me quote you Microsoft Software License Terms (MSLT) for 2007
15. REASSIGN TO ANOTHER DEVICE. You may reassign the license to a
different device any number of times, but not more than one time every 90
days. If you reassign, that other device becomes the “licensed device.”
If you retire the licensed device due to hardware failure, you may
reassign the license sooner.
Thus, IMHO you shouldn't have any troubles reassigning this copy to another device.
There is no procedure for MS OFFICE deactivation. One should simply uninstall software from first computer and then reinstall and activate it on the second.
Should you ever experience any troubles, you can always reactivate vie phone.