Being in the IT world, I'm frequently contacted by family members for help with their computers. And unfortunately, their computers are running Windows 2000/XP/Vista. Why is it unfortunate? Because I am contacted like clockwork, every few months or so, with the same issues time and time again. The top issues that are brought up repeatedly are: a) The computer has a virus or spyware that has hosed the system completely, or b) The computer is running slower than ever. And neither of these problems are fixed in a couple of minutes. It can take hours to clean viruses and spyware or re-install the entire system (if it's damaged badly enough), let alone try and clean up all of the temporary files that Windows leaves all over the C: partition.
As a test, I migrated one of my relatives to Fedora 10, 2 years ago with a new laptop. She only uses the laptop for web browsing, email, basic office documents, and the like. To date, I've only had one call from her, about the computer going into standby mode and couldn't be waken (which was fixed by a kernel upgrade). Everything else she was able to figure out on her own, because she had already used Firefox, Thunderbird, and Sunbird on Windows from before, and the programs are identical on Linux.
So I am seriously contemplating migrating other relatives to Linux as well. There is the initial learning curve, but I think most users will adapt and find their way. Linux (Gnome desktop environment; I haven't touched KDE in years) is laid out in a very logical manner. And, the reduction in support calls to me adds the winning touch. One of the more aggravating things is the time wasted not only on their end, waiting while their computer is down and being fixed, but my time that is flushed down the drain fixing these constant problems. I can never get that time back, and I'd much rather be using that time doing something of my choice. Linux basically runs itself. Tmpwatch cleans out the /tmp directory based on file dates, and most applications don't store other temporary files all over like they do in Windows. And viruses and spyware are pretty much non-existent in Linux. And the Linux kernel is so efficient that overall Linux just runs better right out of the box. The only hurdle I can foresee is gaming. Some Windows games may be a challenge to get working in Wine. But for basic users that only need the basic native Linux applications, migrating seems like a winning solution.