At the time, I was running Windows 98 on my PC, and wanted to move to Windows XP, which had just been released. Unfortunately, the drivers for my sound card and some other hardware was not available for XP (or even Win2K), so I figured "why not try out this Linux thing instead?"
I had had some limited experience with Suse 6.4 some time earlier, but from reading about the different distros, I decided to pick up Mandrake 8.2. I downloaded the whole CD set and even printed covers and everything for them. From there, I've used Debian, Gentoo and Arch. I'm pondering trying out PC-BSD next, it seems pretty nifty, and I'm getting too old to constantly tinker with my main desktop OS.
I lasted a year or so running Linux exclusively (and playing a LOT of Quake 3) before I buckled and added a Windows partition again. I'm pretty well satisfied with Windows 7/10, actually. Very good OSes, if you must run Windows apps.