If I have a machine say FOO and I want to retrieve all web services on that machine how do I do it?

I can use WS-Discovery and I know how to do this with the .NET 4.0 Discovery API. However, the only sample I could find is multicast, which in my use case is not sufficient because:-

1. I already know which machines may be hosting the service.
2. UDP multicast is going to be unreliable given that I have potentially many machines on the network, but I am targetting only a limited subset.
3. Managed mode with a proxy is not going to work either, because this is yet another "pre-requisite" I have to setup.

This should be easy right? Startup, send a message to one or more machines and wait for a specified period of time for a reply.

For some reason, however, that doesn't suffice. Any ideas?