Whatever you go for in the end this info might get some discounts:
"You may be able to upgrade your spec if you use the following voucher codes and maybe get the 5% discount. The current expiry date on that voucher is 28th September but they seem to update them regularly. This thread on boards might be of interest also as you may be able to avail of the Employee Purchase scheme with Dell and get a further discount"
I'm not saying that your Mother would qualify (age wise) for this Age Action Computer Training programme but it might be of interest. If she did it might be an idea to get the training and let her decide for herself what type she would like or Age Action might have recommendatons.
Hope it works out better than trying to teach my Mother and Father to text