How to monitor the Networktraffic / dataload?

Howdy,
One small question .. I haven't searched it in the FAQ cause I think it is a old request but with new Hardware ... but let me explain what I mean.
We got IBM BladeWorkstation .. and I want to check the Network connection between the Blades and the Thin Client. .. The Balde is not the Problem cause it is more less a normal PC (XP32 and 64 bit), the ThinClient is more tricky to finger out, cause no OS on it :-(. My problem is that I dont know what is the easiest way to search for this data load (Networktraffic ). I think it is by the switch, isn't it?

So is there someone who has a good idea how to get a nice output of the BladeCenter included Switches ?