What would be the ideal network setup for a several terminal practice?

We currently run a windows 2003 terminal server with 6 workstations running Rxworks. I am a bit linux illiterate.

But :

I want to get away from Windows server and its licencing but still be compatable with the workstations we have.

Is it possible set up Linux in a terminal server type of setup?

Is this necesary? or is the browser conection in OPENVPMS the equivalent anyway?

What is the best server setup? Ubuntu? Windows Peer to peer? Windows Server?

Is Ubuntu easy to set up as the network backbone ie- DNS, DHCP, Domain controller, file and print server?

Can you set up ubuntu server that is compatible with windows workstations conecting to it?

Would it be easier to just set it up on our existing Win 2003 terminal server?

Thanks

Rob