Ubuntu

Ubuntu Server Edition does not seem to be stable enough for production use.

What we have have found is that Ubuntu Desktop with GTM and VistA installed makes a great development environment, and can be used to access VistA as a roll-n-scroll user. --Steve Watson

Here is some info on how the UNIX filesystem should be laid out:

Filesystem Hierarchy Standard

Using Linux with Active Directory Server 2003

Linux Active Directory How-To