need a network monitor

Im sure this has probably been asked already, but I havent found it yet,and its getting to be a problem.
Im looking for a easy (newb) network monitor to track in and outbound connections. Im having constant internet traffic that I didnt initiate. Ive tried using task manager to see what is causing this with no luck.
Im currantly running
win xp sp2 completly updated
Avast anti virus
zone alarm
spybot resident protection
u torrent is installed but not running and all torrents deleted.
Some how I let something get past the firewall and Im not sure what it is.
I figure if I can see where the traffic is going I should be able to find the culprit.
Since im writing this in a bit of a hurry I may have left something out so I will provide more info if needed.

Pick up net tools thats all you need, lots of goodies for ya