I just got a HP DL360 Server.... What comunications manager version would you install

I just got a HP DL360 server for next to nothing. I want to run it as a real communications manager in my lab. What install would you put on it? It alreay has windows 2003 server, so I was thinking of 4.3, but I am up for any suggestion. What would you install on this hardware?
Brocade: BAIS, BACNS, BAEFS Cisco: CCENT, CCNA R&S CWNP: CWTS Juniper: JNCIA-JUNOS
CompTIA: A+ (2009), Network+ (2009), A+ CE, Network+ CE, Security+ CE, CDIA+
Mikrotik: MTCNA, MTCRE, MTCWE, MTCTCE VMware: VCA-DV Rackspace: CloudU
CompTIA: A+ (2009), Network+ (2009), A+ CE, Network+ CE, Security+ CE, CDIA+
Mikrotik: MTCNA, MTCRE, MTCWE, MTCTCE VMware: VCA-DV Rackspace: CloudU
Comments
CompTIA: A+ (2009), Network+ (2009), A+ CE, Network+ CE, Security+ CE, CDIA+
Mikrotik: MTCNA, MTCRE, MTCWE, MTCTCE VMware: VCA-DV Rackspace: CloudU
you can install CUCM 6 and 7 on VM cisco allows that for testing purposes