Re: which is good on an older computer
I have only a Gig of Ram myself and a dual-core processor, and Xubuntu 12.04 runs like lighting on it. But feel free to run the newest ones or older ones. The newest ones can have features quicker to it, but you get more security updates on the LTS for a longer time, meaning you do not need to upgrade every 9 months. Ubuntu 12.04 would run fine on that system. Kubuntu starts out with a menu and task bar system set more like Windows. She might like that more. Try them out.
The simple believeth every word: but the prudent man looketh well to his going.