Tom Dalton :: Doer of Good

For checking out which ports are open on a given system, Nmap is a slick, simple little tool. It runs from the command line, so you have to learn the parameters to put in, but the basic run is just:

nmap 38.119.178.86

or whatever target IP address you're looking at.

http://www.insecure.org/nmap/

The windows executable installer includes winpcap which is the magic driver piece that lets you do all sorts of network fun.