|Kind of nice of you.|
Not worth the upgrade for you to do it. Sell (donate) the device and get a new one with xp installed maybe.
Seems any kid would be able to use Linux. Might be easier for her to just learn linux? Even my wife can use it, well.. she can as much as she understands windows.
Be sure you have a way to boot the system. Some of the newer net things are usb boot, without any cd drive.
If you have a cd drive then I'd use HOME instead of Pro. She really has no need for professional.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10