I definitely recommend starting out on Mandrake.
As for learning a little bit about Linux, check out the stuff I posted here:
http://www.tfproject.org/tfp/showthr...ighlight=linux
Obviously, it's more than you'd need to know to just mess around with it, so you probably won't go through all of it. But it'll give you a basic understanding of a lot of Linux fundamentals. The internet is pretty much capable of taking care of anything else in my experience. If something comes up and you don't know the answer, just search for it. I also recommend setting up a filter in your e-mail account and signing up for the mandrake-newbie mailing list. It's a great source of help and I was able to figure many things out because of it when I first started to seriously use Linux.
Lastly, I recommend reading this to make sure that you don't have any misconceptions of Linux and that you're wanting to use it for the right reasons:
http://www.tfproject.org/tfp/showthr...ighlight=linux