Hehe, my experience was kind of similar. I was not really unhappy with Windows (98), I had just grown curious about Linux due to all the media hype it got at the time (2000-ish).
After I got past the initial "This is really weird"-phase, Linux was an eye opener. Other than that I use Windows at work, I have not looked back since.
Strictly speaking it is not about GNU/Linux per se, but Windows vs. Unix. One of the BSDs could fill that place just as well, but on Linux, hardware support is usually better, plus the mainstream Linux distros tend to be more friendly to lazy or non-techie users.