lazyengineer, Active Directory is Microsoft's version of NDS. It is a program that allows Easy Administration from a single point. ADS is still in its Infancy compared to NDS which has been around for years. ADS came out with Windows 2000. IN NDS and ADS you have your servers, domains, etc. in one place. ADS is required to use Exchange, and numerous other server programs. As well as allowing access to NTFS drives from Windows 9x. But, as I said you can use IIS, though it is insecure to share your drives over the Network as an Intranet. Add the drives as Virtual Directories, then access them from IE by typing http://192.168.24.1/{virtual directory} or if you set up DNS then http://{host}.{domain}/{virtual directory}.
As for Linux, I installed a copy a few years ago and dumped it within a few weeks. Half of my hardware wasn't supported, including both my Network Card and Modem. It didn't properly support my Video Card and the screen looked like shit. It was a pain to set up, but was doable. The GUI seemed rather primitive. I did better using the command line with Unix commands than Navigating my way through their GUI. I could have dealt with the video, but I couldn't remotely access (telnet) due to my NIC and Modem being unsupported. I got a copy about a year ago that was easier to use, but still didn't support half my hardware. For the most part I can count on Novell and MS to support my hardware. Linux is free, which is enticing though. Both MS and Novell cost about the same, though Novell isn't as Anal as MS ala Activation. And Novell has about the same specs as Linux unlike MS which has outrageous specs. Or Windows XP, which is a resource hog. I installed NT 4 Server, 2000 Server, NetWare 5.0, NetWare 5.1, and Linux at various times and tended to dislike MS and Linux. Novell takes some learning, but is easier than Unix/Linux and a hell lot more Secure than MS Windows.
Here's a joke: Why does MS call it Windows ?
Because all you have to doesn't take much to break in.