How to sniff usb port under Windows?

From time to time I need to dump usb traffic under windows, mostly to support hardware under Linux, so my primary goal is to produce dump files for protocol analysis.

For USB traffic, it seems that SniffUsb is the clear winner... It works under XP and has much nicer GUI than earlier versions. It produce huge dump files, but everything is there.

However, my device is in fact usb serial device, so I turned to Portmon which can sniff serial port traffic without USB overhead.

This is my first question on stackoverflow, so let's see how well it goes...