Newbie requires knowledge!??!

Hi guys

Firstly, let me explain my background. I have spent a few years as a developer (VB6/C#). I came out of the industry in 2007. I am now looking to re-enter the industry, but this time as a network and systems administrator, I do not want to do programming. I have plenty of questions so if any of you guys can help, I would very much appreciate it. Please note I am looking to study areas most useful to employers and to help find employment. Here goes...

I am currently studying the CCNA but I understand that it goes hand in hand with server administration.
1) Should I learn Windows Server or Linux?
2) Maybe a bit of both, which version of Windows 2k3 or 2k8 or SBS (are companies using WS08 or sticking to WS03)? Which version of Linux (Redhat, Ubuntu etc - baring in mind I want to learn a version of Linux that companies would look highly upon)?
3) Why do companies use both Windows and Linux servers (are some better for particular services)?
4) Which scripting language is most in demand to learn (Perl, Python, Powershell, TCL etc)?
5) Can anyone suggests any good, recent, books to help study for the Windows Server and Linux?

I am completely lost on where to start but I do have the drive to start. Providing I have a direction (help, possibly from you guys) I will study study study and then hopefully being confident in this area.

Thanks in advance. Ben.