Cool, glad to see you are up and running and starting to play around.

Samba was covered below for Windows file sharing. The "dir" is an alias of "ls -al" that is set up by default in RedHat.

As for different distros, the Linuxes are a little different, but most of it is "look and feel", under the hood the kernel is the same. However, FreeBSD is NOT Linux, it is another OS but out by Berkley. There are actually several distros of BSD as well, FreeBSD, OpenBSD and NetBSD are the more common. They are unix variants as well that run thier own kernels, not Linux Kernels. The file system is similar, but still different on the lower levels. BSD is worth looking at as well, should you get the time. I like it a lot, but that is my personal preference, evaluating the different OS's to make an educated choice on a preference is highly recomended :)

Good luck, I hope you don't get too frustrated, once you pick up the basics, you might start really liking it.

One other tip I have for learning any OS fast, use that machine for everything you do on a daily basis, e-mail, surfing, working, everything, this will force you to start learning more and more.

"Nothing is sure but death and taxes" I say combine the two and its death to all taxes!