Elizabeth has an old Dell Inspiron and her hard drive is all full now so she can't run it. Leo says it's not really worth upgrading the machine. It would be cheaper to pick up a Chromebook for about $400. Leo recommends the Acer Spin. The Spin 11 is $330 if money is tight.
She can then use either Google Docs or Microsoft Office Online. It'll be far more secure that way and save money in the long run. Trying to upgrade an old computer really won't help Elizabeth.