You need to see if you can get Ventrilo and MS to run off a differant port. If googleing for answers doesn't work checkout the sleepywood forums. They might be able to help you with MS, cause i'm sure tons of them have had the same problem.
Edit: well i was looking at SW.net cause I expected to see a stickied thread. Infact one of the threads i seached a Mod locked the thread and said they wouldn't help him violate the agreement to use the internet with their school. I think some people don't realize alot of people in college live at school.
I think you should look into Tunneling
http://www.http-tunnel.com/html/Ventrilo might be flexable enouth for you to change the ports it uses. (especially since it is your server)