Network Change-Over

I came into a job position where the domain is on a Class C internal network. The ip is 192.168.165.x. This limits the number of hosts that are allowed on the network line. I want to change the internal network to a Class A network, somewhere in the 10.x.x.x range.

What would be the right, and easiest way to make this conversion. Do I simply change the ip on the servers and dhcp? Or will this create network problems?

It is a Windows Server 2003 network. I also have some new servers which have just arrived. They are Windows Server 2008. Will that be a problem as well?

Edited for bump