Odd network traffic with Edgy

[Ed Smits]

I have 2 Dell laptops, both running Edgy, roughly similar hardware.
The older one has been running Dapper and now Edgy for 8+ months, and
I am used to it's behaviour. On both laptops I have System Monitor in
my top panel, set to show processor, network and load. On the older
laptop when I'm not doing anything, and especially when I have no
browser etc open I see little or no network traffic, which is at it
should be (other than Synaptic Update and time/weather checks).
However, on the newer one, which I just started to set up this week I
notice that even in those quiet moments I have what seems to be a lot
of network traffic I can't account for.

1) anyone have any ideas what could be causing this?

2) what would be the best tool to try and monitor/analyze this
traffic, preferably GUI based if possible.

Thanks

ED