In a future post, I'll talk more specifically about how to be a good "Linux at work" advocate, but for now let me talk about how to move your family to Linux.
I've been a Linux user since 1993. But it was a few years before my wife decided that Linux was something she could use for herself. I helped my wife migrate to Linux (from Windows) after she finished her Master's thesis. Before, on Windows, she experienced regular crashes and lock-ups, and other weird behavior. Now, on Linux, everything runs fine. My wife uses her laptop to do email, write docs, browse the web, that's it. Not very complicated, so for her it was an easy move.
I did the same for my mom several years ago. My step-dad thought himself a great PC technician, despite knowing nothing about computers other than "point and click". So the PC was often hosed, usually through some malware problem. They used the computer just to browse the web, check email, write docs, do spreadsheets (home finance), play solitaire and freecell, play Flash games, watch Youtube. It was an easy move for them to migrate to Linux, and they've been problem-free on Linux.
The key in making the transition easy is for you to understand their computer use, what they use the computer for. In my experience, people who are "casual" PC users aren't doing anything that couldn't be done on Linux. Note "casual" ... with the people I support, that means no World of Warcraft, no Half Life 2. Just basic computer use, and simple "diversion" games. (PC gamers find it more difficult to move off Windows, because the hot games aren't available for Linux.)
The next step is for you to show your audience that Linux is okay, that it will meet their needs. My wife was an easy convert because she saw me use Linux every day, to do the same things she did. My mom was a little more difficult because I wasn't over there all the time. But if you can sit down with the family and show them how Linux is really just the same as Windows, then you may be in luck. If you have a Linux laptop, bring it with you when you visit for Thanksgiving. If not, consider running a "'live CD" version of a popular distribution, such as Fedora or Ubuntu.
Don't push it too hard, and don't expect to change minds right away. May take several visits, with casual demonstrations of what Linux can do.
When you demo Linux, don't tweak out your desktop. Let it be pretty much default. No odd themes, no cute backgrounds, no desktop effects turned on. That "geek stuff" kind of freaks out your potential audience. You'll note that the screenshot I used to talk about the Linux desktop used default settings.
Show that the same applications exist under Linux, but with a different name. OpenOffice versus "Microsoft Office". Firefox (same). Or Firefox vs IE. Make sure to install the Flash plugin ahead of time, so visiting Youtube is the same experience. I'd turn off Flashblock or not install it, so it's as close to the Windows experience.
If you do this, you might be able to make your family tech support easier. I find Linux harder to break, and certainly it isn't vulnerable to the Windows malware that's out there.