I just set them up with a reliable AV program, and educate them on how viruses are transmitted. They generally prefer that than taking time out of their lives to learn even more IT type stuff that they weren't interested in in the first place to fit some ideology that they could care less about.
There is no all encompassing "Best" solution. Each user is unique. My mother loves her Macbook Pro. My dad is totally enamored with his EEE PC (running Linux). My brother cannot go without his Windows XP based Dell. What I install is based on what I need the system for. I need a server? Linux, in a heartbeat. Gaming system? Windows 7 is whatI am preferring. I would like a Mac for just day to day internet type stuff. Each OS has strengths and weaknesses, and each user prefers different things.
That being said, Unless Macs get cheaper or Linux gets more compatible and easy to use, Windows will continue to dominate the marketplace. Rarely does the technologically superior win, but the easy to use and best marketed.