I have been surfing for an hour or so and had a look at my connection status. I noticed that it is continually sending data, even when my browser is closed. I would gues by looking at the counter that there is not much going out. About 100Bytes/s. Bytes, not kb or kB.
I run lots of security software: spyware balster, adaware, avg, a squared, spybot, zone alarm. Is there something untoward happening.