I can't personally recommend a program from my experience as i rarely use a network diagnostic tool. I thought i might as well throw in my two cents. I found a good link here
It lists a good number of programs which can gather information from the network or improve the security of the network. If this is the sort of program you are after, then hopefully the list will be of use to you. I'm sure other people will throw in their personal opinions
Hope that helps, and don't hesitate to add more infomation to your question as it will help others understand what you are after.
Edited by D-Trojanator, 05 February 2006 - 09:42 AM.