Rather than going to the expense of a HDD, she can run
Ubuntu on her CD
drive using a Live CD. She can either download Ubuntu
(pretty big download)
and burn an ISO or order a free CD from Ubuntu which
will be delivered
postage paid in 2-3 weeks. Using the Live CD she will
get to experience
Ubuntu as if it were on the HDD with the exception
that it won't run as
fast. A small price to pay. As for her XP problem,
she should call MS and
explain the situation and see what they can do for
her. MS should be able
to certify XP ownership from the serial number of her
laptop.