Scott Hanselman's Developer and Power Tools List is truly an exhaustive list of tools you may find useful, you really ought to check it out and see what's out there that can make your life easier. One thing he left off though is Ethereal; a tool that ought to be part of XP (technically, NETMON is part of the resource kit, IIRC). Ethereal rocks all over the place, it reads every sniffer format I've ever heard of, dissects every protocol you'll ever run into in common usage, and is totally free software. Scott does mention YATT, which is a worthy tool, but sometimes just doesn't get the job done. Like when you need to be taught that in the presence of an NTLM authenticated HTTP Proxy, you can't shut off keepalives on a WebRequest...