My mom used linux from the late 90s through the early 2000s. She did not adapt well to using a mouse and windows but wanted to do online shopping so I set her up with a machine that started directly to a full screen browser and dialed the internet as soon as an internet connection was needed. She eventually got good enough with her mouse that she moved on to an XP laptop but I really loved being able to tell people that my mom runs Debian.

My dad and I got my grandmother set up with an EEE PC for sending emails. I don't know if she ever used it (perhaps she emailed my dad, but she wouldn't have been emailing me) but I remember setting it up to be as easy to use as I could (e.g. big icon that said "Letters" underneath for an email application) and writing her instructions.