I could not understand the object of this post
To setup DNS's in Cpanel so that new userss' domains get added to the DNSes in whm/cpanel?
Good question, Fidget! But it needs a multi-step tutorial. You can setup two identical machines as a cluster, yes. But consider load-balancing too. As a small cost-effective fail-over solution, as an ISP use a combination of Squid and Piranha could serve the purpose. Other Clustering software are many these days, openmosix.sourceforge.net is a popular one. I'm talking Linux BTW.
Read this
http://freshmeat.net/articles/view/458/ when you have the time.
Wait for server 2008 which will have a lot of option for "virtual machines" on Windows Side.
In todays world of RAIDs and SANs, data synchronization is not much of an issue.
Hope that helps a bit.
Regds
IJ