Hello bbcaptman, and welcome to Seven Forums.
It depends if it is a OEM or retail upgrade copy of Windows 7.
If it's a retail copy, then yes you can install and activate it on your computer.
Clean Install with a Upgrade Windows 7 Version
If it's a OEM copy and had been activated on her computer, then the key number is permanently tied to that computer. You can try to do a
phone activation, but you might not be able to activate it on your computer with the same key number. It would be worth a try to see though.
Hope this helps,
Shawn