yes, originally they made it in both formats for PC and Mac, I think up to Logic 5, I think they quit making it after that because from what I heard, Mac bought the rights to it.

I suggest starting with Reason. It's fairly simple to use and a good starting point to learn the basics before moving to something more advanced like Cubase. Also, you can use Rewire to hook Reason into Cubase to make use of some of it's sounds and features.

I've never used Logic. All my experience is with Acid, Fruityloops, Reason, Buzz, and Cubase SX.