This was shamelessly stolen for another blog guys, but its worth repeating

"UCCX

So far, UCCX has been running on "Cisco OS" 2000/2003, which in fact is Windows 2000/2003. However, UCCX will refuse to install if Cisco specific registry key is missing. Follow instructions on http://www.tek-tips.com/viewthread.cfm?qid=930128&page=1 to add the registry key.

Good news is: VMWare is supported since Cisco OS 2003.1.4. If you're using OS 2003.1.4 or newer, you don't need the registry hack.

Another tips is: if you want to bypass the hard drive/memory requirement check, you may create an empty file named "crstest.ini" on C:\. Then CRS won't require 72G HDD/2G memory to install. Of course, this is for testing purpose."

From:

http://htluo.blogspot.com/2009/07/cisco-software-on-vmware.html