I've used Linux on my desktop off and on for the last 4 or 5 years. Most of the time I'd install a distro just to try it out and see how improvements were coming along. I 'grew up' with windows on my desktop, but when I got into web scripting languages Linux became my server of choice. Until about a month ago, 99% of my desktop time was in windows, because I saw Linux mostly as a great server option and a limited desktop option. This past summer some business associates bought me a Vista machine for web development. About a month ago, I had gotten so fed up with Vista that I was on the verge of installing XP. To be honest, this was mainly because my web development machine wasn't gifted in the area of RAM and Vista used nearly all of it just to boot. The day I had finally entirely, without a doubt given up on Vista just happened to be the day after Gutsy Gibbon was released. So, I decided to try the live CD, before deciding for sure I was going back to XP. Everything seemed to work perfectly.
I used the one useful thing Vista had and partitioned my drive, installed Ubuntu, and started using it. Since then, I've only had to boot into Vista one time, and that was to copy some bookmarks and things like that. I've been completely happy with my linux desktop and the choices it gives me. I miss some of my games, but when I have time to play them again, I can use cedega or something of the like. I still plan to upgrade my RAM, but it's not a necessity like it was before. I like the idea of giving out live CDs and letting people try Linux. I think the approach will probably be more effective on friends and family, but you never know.
I'm a Windows user, and I've been sober for almost a month ;)