[stomachmonkey]

I would not advise at this point in her life moving her to an OS that she is unfamiliar with.

Linuxmint is great but still requires more knowledge than Windows.

If she'd never used a PC before that would be different as there is no untraining to do.

Both my kids got laptops to play educational games at young ages.

For them a computer is no more difficult to use than the TV remote and they switch seamlessly between OSX, Windows and Linux.

I don't think there is enough difference between XP and 7 that she'll get to confused.