I saw this had been published and thought I would share - it is an amazing tool that I use for diagnosis all the time.  Reading http://www.ditii.com/2007/07/03/network-monitor-31-released/ it also reminded me that this includes traces on wireless networks!!

Microsoft Network Monitor 3.1

Network Monitor 3.1 is a protocol analyzer. It allows you to capture network traffic, view and analyze it. Version 3.1 is an update and replaces Network Monitor 3.0. Network Monitor 3.x is a complete overhaul of the previous Network Monitor 2.x version.

• Supported Operating Systems: Windows Server 2003; Windows Server 2003 x64 editions; Windows Vista; Windows XP; Windows XP 64-bit

It is suggested that you have a CPU of 1GHz or greater, 1G or greater of Memory and 25 Megs of available Hard Disk space, plus room for capture files. Supports Vista 64 bit as well as 32 bit.

Instructions

Network Monitor 3.1 can co-exist with Netmon2.x. NM3.1 installs in %program files%\Microsoft Network Monitor 3, so there is no conflict. But it will require that NM3.0 be uninstalled first. The NM3.1 install will do this automatically for you.
For Vista, we have a new driver that supports new features available in the NDIS 6.0 driver. If you are using tools that rely on Network Monitor 2.x NPPTools, these tools will no longer work.
Capturing on Vista requires NM3.0 or NM3.1, as Netmon2.x does not capture properly on Vista.
Warning: Capturing with the NM3 GUI with conversations enabled can use up considerable amount of memory. This may cause a machine to become unresponsive. If you need to capture data for long periods of time, please use the included command line utility, NMCap, and the /DisableConversations switch.

Download details: Microsoft Network Monitor 3.1

ttfn

David