Bill bought his mom a new flat-panel iMac for Christmas. It's a fine gift from a son, but it wasn't entirely altruistic. She had a Windows computer before, and he had to fix it all the time. The Mac will require less work from him, so when he visits his mom he can talk to her instead of wrestling with her computer's operating system.
Before we introduced my in-laws to the Mac in 2000, they'd never really used computers before. They're still running the same old iMac, with the same basic Mac OS 9 installation, as they were four and a half years ago when it was brand new. I've performed some upgrades, installed some software, and fixed a few things, but nothing major. They hooked up their own cable modem too, and it continues to work fine. But I fear to think what their system would be like if it ran Windows. They probably would have given up on their original machine once it reached Cruft Force 6, and bought one (or two) replacements by now.
If you're still stuck fixing your parents' (or cousins', or friends') Windows computers, here's some good advice on what to do. Or you could take Bill's route and get them (or at least have them get) a Mac. (If you're brave, you could install Linux for them instead, but if you're the sort who's inclined to do that, you're probably way ahead of me on this train of thought.)