I don't really know the answer to your question but I believe that the download would come through a link supplied to the e-mail that purchased the product.
Also, a great number of people have had trouble with the downloaded upgrade file. You are better off paying the extra $ for the disc and you can send her that.
I wish she had XP. Its Vista and I just want it gone. I agree about the disc, but its Mothers Day and I sort of need to get something to her today.