You're using C++, right? It depends on what information you're trying to communicate to/from the PC. If you don't use the dashboard interface, then you'll want to use sockets. Lookup how to use sockets, its mostly the same interface as every other OS.
If you use sockets, you get to pick the port that you use. We have a webserver running on our robot that we use to communicate with it. The code for it uses the portable boost::asio asynchronous I/O library to abstract all the socket crap away. But, asynchronous I/O is inherently tricky, so user beware.
http://code.google.com/p/webdma/