To install Cisco Call Manager 4.1 or IPCC Express 4.5 on Windows 2000 Server, All you need to do is add these settings to your registry.
This setting is to fool Call Manager thinking that it is a Cisco MCS or compatibale hardware.
This setting below are OS requirement for Call Manger.
[HKEY_LOCAL_MACHINE\SOFTWARE\Spirian\System Info\OS Image]
Version = 2000.2.7a
I havent actually tried it on a Windows XP or any other OS, but I think it should work and get installed after adding the above settings to your registry.
Try and let me know your feedback.