Comment Easy (Score 4, Interesting) 418
1. Install logmein (logmein.com) - the free edition is just fine.
2. Make your mom a standard user. Non-administrator.
3. Create an "Admin" account. Do NOT tell her the password.
It's working so far for my mother-in-law. Her old computer was so badly infested that I just gave up and gave her one of my spares. (She had no reload media.)
Now, even with her teen grandson surfing porn (yes, I caught him at it, yes, we had a long talk about it but I doubt he's stopped) it seems to be clean.
She has Windows 7. Maybe it won't work as well with XP.