I'm not certain whether you want to use a server to install an OS from an image, or have the computers PXE boot installing the OS at boot time.
For the former, you might want to look at the FOG project:
You could use this to install an OS to a large number of hosts simultaneously. This is a Linux server, but you can install MS Windows hosts.
For Linux/Unix, you can use NFS ro mounted directories for directories that are static. This will allow you to use the same libraries, programs, and system settings for the Linux hosts. The LFS standard would be a good starting point. The hosts can be PXE booted, loading the kernel/initrd file when they boot up. In the initrd environment, the NFS shares are mounted, and
Another solution for Linux is to use thin clients. The clients will PXE boot X.org terminals, which display a person's session running on an application server. These devices can operate very efficiently on only a few watts.