I started in IT too, for the same reason. Because I was good at troubleshooting Windows issues.

My career took off when I got a job at a startup, where the IT group was in charge of not only all of the desktops, but also all of the unix servers, firewalls, routers, etc.

I got lucky that our senior engineers were great mentors, and would allow us to take on less critical projects that used those other technologies.

Also at the same time, I vowed to use only Linux at home as my primary desktop, which forced me to learn a lot about admining unix boxes. I'd take the old servers home that were going to be tossed and set them up as web servers or mail servers.

So I'd say try to find a job with a small IT team that has other bigger responsibilities.