I'd probably try Mandrake as a first-timer Linux distribution.

Probably the best way to learn is to simply pick something that you need/want to do and just do it. When you hit a stumbling block, ask some questions. That's basically how all Unix folks learned how to do it. It's a good point that we were users first, then admins.

Personally, I have the same feelings about Webmin and other fancy GUI addons to configuration changes as someone else had about FrontPage. It may get it done, but you won't be learning anything and there might be some weirdness behind the scenes.

And, for the record, Unix is a set of operating systems that work similarly and present the user with a very similar set of tools. There are two main branches, System V (pronounced "five", not "vee") and BSD, being commercial and educational varieties, respectively. They're mostly the same, but have quirks of their own. Linux is an attempt to clone Unix. It inherits quirks from both SysV and BSD, annoyingly. But for the most part, they're all quite similar while retaining certain differences.