I was all up into the MacOS (pre OS X), and I'd heard that Apple was taking the system to a Unix core. I'd experimented with a few Unix commands at work, but wanted to own the system. That is; to run it as my own, like I had done with Windows and Mac and even the old Amiga I ran for 8 years.
The whole Linux concept was intriguing to me because of the low cost and open community. It was a daunting experience (at first) to actually go and download a Linux distro though. I went to an FTP site and saw all these files sitting there and said to myself Oh boy... What the hell am I gonna do with all this?! Never afraid to bite off more than I could chew, I dove in with (the now defunct) LinuxPPC. Found lots of help at LNO, after trying the various mailing list and such (and having my ass handed back to me many times).
It's been a slow process, but I still won't quit. Linux hasn't left the "hobby" stage for me yet, but I'd like to keep doing more with it all the time. Just built my first all Linux box last year, but because of limited time and space, the system is locked away in storage right now. I hope to have all my systems up and running again before summer though, and have Linux installed on all of them.
I started using Linux because I joined this LAN crew as a web designer, and most of the guys were Linux evangelists. Downloaded Red Hat 6.1, tried it, and liked how it was so different. Then two weeks later I tried Slackware, and found it to be easier.
That was four years ago or so, not sure, and I didn't really do much in it until last year. That's when I actually looked at the system in depth, and started seriously learning how to use it. I don't even feel comfortable in Windows (WHERE IS THE NATIVE VIRTUAL WINDOWS DAMNIT!).
Linux is faster, so customizable it hurts, and I can get it working the way I want.