I've always used Windows. Well, no, I tell a lie; I've always used Windows on my desktop PCs. I happily use Linux for servers, because it's pretty straightforward to set up and administer. But I've never got round to using it on a regular basis for my day-to-day computing.
Sure, I've played about with it and installed Ubuntu on an old laptop, but it then sat in the corner gathering dust. The fact that it wasn't the best laptop in the first place, meaning the experience was slow and visually unappealing, is what's probably put me off being more bold and installing it on a main PC.