cmwade77, unfortunately, it's not that simple for the Air.
The original model uses a PATA-ZIF connector, but the Rev B & C use SATA-LIF connector. You'd need some sort of adapter (or 2 or 3). A quick google search yields a few results that you might check out.
EDIT:
This site seems to have several adapters, although to make a better recommendation as to
which specific adapter, can you tell us which model your GF had?
EDIT 2: Also, if she's getting a new Air to replace her old Air, assuming they're the same model/spec, why not install the old drive into the new computer and then you don't have to restore anything. (Just get an external drive for backups in the future).