University Campus Managed Desktop systems run the full Windows system, just as Microsoft publish it: this means that peripheral services like MSN Messenger are available on staff and Cluster Room PCs.
ISS make such peripheral software available but do not support it: means that there is no guarantee of service or advice.
Video chat is not available.
There is a useful list of Instant Messaging programs at the Docking Service web page which lists applications: see Instant messaging about half-way down that page.