I'm a 100% open source guy, for my own use anyway. Wireshark shows all traffic on a segment, the source and destination, ports, what protocol etc. I assume this app you mention is similar?

There's a really nifty graphic mapper called etherape, but it's less useful ultimately because you can't save any of it's output.

The real conversation piece is driftnet. Sit in a wifi hot spot and sniff images out of the traffic, you literally see the images other people are seeing in their browsers. (certain file formats anyway)

I strike up conversations with folk at wifi hot spots about their computers and security. When I show them pictures (on MY screen) that they were just looking at on theirs they have a tendency to listen. =)

Not sure if there are win32 versions. I think there may be, and I'd guess they'd be open source also.