Was that a question for me? Anyway, I'm not familiar with Server Core, but after reading some documentation [1], it looks to me like a Linux server without X11 and extra services which is quite the norm.
I worked as a sysadmin, most of our machines were virtual machines that ran either Debian, or Ubuntu Server LTS.
We also had a few CentOS machines as well.
Ubuntu Server was bigger than Debian and CentOS,but only one of them had any kind of graphical interface. And that was only because my Boss insisted since he refused to learn to use a command line.
It was normal for all of the machines to only have init, sshd (non-standard port, no password), iptables(it was a while ago, ok?), security measures such as fail2ban, monitoring scripts, and whatever service they were running.
That was usually it. If I could strip any extraneous services that weren't needed, I did so and saved the image as a template for next time. My bosses loved me since when I started, most of the machines had 512Mb-1Gb of RAM allocated(mostly unused), and I managed to drop the necessary RAM down to about 128Mb for the services that didn't require more. Internal websites, DNS, etc.
Since We had a couple huge machines running most of the VMs, I also set up a pretty large dedicated RAID0 for /tmp space, and set the VMs to aggressively page to disk. Our Giant Email server used to require 7+ Gigs of RAM for all of the work it did (We're talking massive amounts of email constantly here, at least 20 domains serving multiple businesses), but I dropped it down to 2Gb. No loss of reliability or noticeable speed, and it freed up lots of resources for other machines to use.
tl;dr Linux Servers are usually as tiny as they can possibly be without affecting speed or reliability. Also due to the sheer amount of tweaking you can usually get the most bang for your buck with only a week or two of tweaking.
MS Server needed at least 1Gb last I checked, but that was a while back. You can have literally 8 Linux servers for the same resources as one Windows Server.
> And that was only because my Boss insisted since he refused to learn to use a command line.
I'm certain I'm going to get crap for this, but your Boss had no business being near a server if he wasn't willing to get with the program and A) Delegate B) Lead by Technical Superiority. I feel really weird to say this, but I get the "non-technical technical manager" now because what they're supposed to be doing is MANAGING and not doing technical things, because they fail at "doing" and are suposed to be good at telling people what to do and tracking progress/etc.
[1] http://msdn.microsoft.com/en-us/library/windows/desktop/hh84...