I'm coming from a mainly Linux background, and need to get to grips with the Windows environment: Active Directory, Domain Controllers etc. Can anyone recommend some good resources for an absoloute beginner on these subjects?
I would try Technet at microsoft.com, and do a search on Active Directory to get some good basics. I also found the Active Directory book by O'Reilly very useful early in my Windows administration career.
You can get started right from Microsoft:
Microsoft's Technet forums are also a great place for quesions - http://social.technet.microsoft.com/Forums/en-US/categories
Other then those AD has gone through a few big improvements since Windows 2000, I would suggest any AD/Windows server books based around what your AD is built for (2000,2003,2003R2,2008,2008R2).
Also I think it depends on if you want book knowledge or practical knowledge. Here are some good resources you might not find on just googling around. You'll notice a lot of them are from technet, but technet I find generally too large for browsing.
Also if you are familiar with linux ldap - AD will come a lot easier to you. A good place to start might be learning about the different roles of AD.
AD AD Blog: blogs.technet.com/b/ad/
AD powershell blog: blogs.msdn.com/b/adpowershell/
AD services team: blogs.technet.com/b/askds/
Brian Desmond: briandesmond.com/
AD tools: blog.joeware.net/
Jose Barretto: blogs.technet.com/b/josebda/
Open a socket: www.open-a-socket.com/
The life of Brian: msmvps.com/blogs/ad/default.aspx