Sounds like you need a network sniffer. There are a whole host of them. the Sniffer (tm) product I know recognizes some of the TDS packets correctly, or at least the last time I used one for a trace it did. But that was a few years ago. You'll also need some assistance from your network folks on that one. However if you have someone who is somewhat adept at reading network traces, Ethereal is open-source and awesome. Sniffer (tm) is expensive. Most folks use Ethereal because it does just about everything most folks want. Be warned, using sniffers without prior permission is often a firing offense. Make sure you get permission first.

If you want to stay on a strictly SQL Server road, look at SQL Profiler (in the SQL Server client tools). It probably does what you need. SQL Profiler can be sure to capture all the events that occur on the server, but it is using the server side.