Windows 2008 R2 Server Core Disk Space Requirements/Recomendations

I'm in the preparation stage to roll out a few Windows 2008 R2 Server Core in my VMware ESX environment.

In looking over the documentation it looks like Server Core can operate in a little as 6.5 GB of hard drive space.

Less disk space required. A Server Core installation requires only about 3.5 gigabytes (GB) of disk space to install and approximately 3 GB for operations after the installation.

I am curious as to anyone’s real world experience and recommendations with regard to this requirement. Is it realistic?

A little bit about our environment:

Less than 25 users, and around 75 computers/servers in our current AD system. These systems will be responsible for normal AD operations and print servers for 5 printers - nothing to big here.

The base W2K8 installation Guide says that while it only needs 10GB to install but 40GB is recommended. That phrasing is significantly different to the Server Core document ["3GB is required for operations"]. I've never tried running Server Core for long with a tiny system volume but I can certainly say that running full blown Server 2008 for an extended period on less than around 40Gig plus enough space for a page file (unless it's on a different drive) is not a good idea.

Increasing the size of a W2K8 System drive is not difficult so you could take the risk but I wouldn't do that unless you know you will be able to increase the volume size relatively easily in future if the worst happens. The way I look at that I'd be strongly inclined to allocate the space now if space is tight. Is the 10-20GB that you're trying to save really worth it?