Yeah Wireshark is a good app. I used it when it was called Ethereal. I've never used the windows version only used it on linux. Which OS are you running it on? I was wondering if there are any differences really.
The only real difference I see between using Ethereal on linux and windows, is what you can do with the network information once you gather it.
It's one thing, to see if there is rogue processes using network resources, it's another thing entirely to be writing and testing programs that use the network stack. One thing that I was using it for was to test the modifications I was making to the TCP/IP stack athe time. Never be able to do that on a windows box!
I've never seen a stateful packet filter for windows that even comes close to iptables.
If you are serious about using ethereal tachyon, you really should be testing\developing on a platform that you can easily make use of the data that your collecting. Btw if you are running linux, check out packlib.
