What exactly is the power of Unix vs. say 64-bit Win2008 R2? The file system? I'll buy that, and that matters if you have a shitload of files. Anything else?
The shell, for instance. It's much easier to get things sorted out in the command line than on Windows and Remote Desktop is a pain in the back. Once you're familiar enough with the shell and shell scripting, maintaining Windows servers can get very frustrating. I know that there's Cygwin and PowerShell on Windows but in my opinion they really aren't as useful as a native Unix environment.
Another one is the easily accessible documentation in man pages. I don't think the Windows documentation and the KB articles are nearly as well organised as the man pages.
Performance-wise, there really isn't that much difference; the latest versions of the Windows, Linux, *BSD and Darwin kernels are equally capable in my experience. In fact, I wouldn't recommend against NTFS as file storage; we use it to store a very large amount of data on Windows 2008 servers and we are very happy with it.
From what I have seen PowerShell is woefully underused and unmastered by many, many folks working in the MS stack. Probably because it is so much easier to use the GUI for everything.
The MSDN site has always sucked, and it's almost always better to Google searches for MS tech help than search within MSDN or the knowledge base. (I frequently find the MSDN article I need from Google. In fact there is a MSDN search widget available for iGoogle!!!) Language and framework docs, help, and searches from within VS are quite good, and from what I've seen of VS11 beta, even better. Also SQL server docs are good.
Powershell is awesome. Piping collections of objects instead of lines of text makes half of the great unix utilities (grep, sed) irrelevant. I used to gripe about the command line itself (Bash's tab completion, for example, trumps) but this is more than fixed by Powershell 3's ISE (in Win8).
Doesn't address your remote access... SSH is really nice and lightweight and the fact that Vim works is great for real sticky problems. Powershell has a remote access mode but I can't say I know much about it.
