Some things to consider on a laptop> the larger the screen the less time the battery goes between charges and the heavier it is and harder to sit with on your lap, The first thing I would do is take her to a brick and mortar store and let her look at 15.4 and 17" wide screens, I think she will like the 15.4 overall but you never know when it comes to Mom(or Wives for that matter), You have to figure out how much time she needs to stay unplugged to determine if the standard battery is ok or if she is just looking to be able to put it away and uses it near an outlet most of the time that will be less important.
http://configure.us.dell.com/dellsto...=DNDWPA2&s=dhs
http://www.shopping.hp.com/webapp/sh...dv6700t_series