Right now I'm a network admin for a midsize company. It was great at first, but now its turned into nothing more than babysitting. I'm not really learning or doing anything new and exciting. I was looking into getting into the security field.
Right now I have pretty much zero *nix experience, so I should probably crack open a book, and start messing around right? There are already quite a few books that I'd like to look into in regards to security and such, but I'd like some advice from those that are already in the field.
What areas should I focus on in the beginning?

Another question that I've been wondering about too...
As far as OS's go, what is the prevailing one that security apps are run on? I know a lot of you are *nix fans and everything, but would someone who runs security apps on Windows be laughed out of the office?
What do you think?

Thanks for any advice or answers!