Question : Excessive XP Packet Activity

One of my machines is registering an excessive amounts of packets being sent. I have a bunch of XP/2000 machines networked as I'm studying for 70-210. They all seem to work fine and can all communicate well. One machine, which is my main machine, I happened to check the other day and the packets sent read around 500 billion. I rebooted and it picked up where it left off. Right from a clean reboot it started reading about 500 billion packets sent. I left the machine over night and in the morning it read over one trillion packets sent. Rebooting bought it back to about 600 billion. I thought rebooting would pretty much set it back to near zero, as it does that on all other machines. To test, when I would go out to a web site and watch to packets sent and recieved, the sent packet would jump a couple of billion instead of 10 or 20 when I would just go to a site. The recieved packets seem normal; a couple of thousand. There's not much in the start up but Zone Alarm, Nortons, a pop-up stopper and some printer drivers. Even if I were to stop all the programs from starting I don't think that would effect the packets already sent. If I check processes running in task manager all that shows is Idle and Task Manager with normal percentages with the CPU usage around 0-7% . Activity light on machine doesn't indicate that it's churning out packets either. The nic is an integrated Intel Pro/100 on a Gigabyte MB. All machine connected through a Linksys router into a cable connection. Any and all help appreciated.

Answer : Excessive XP Packet Activity

Run a protocol analyzer such as ethereal (its free
http://www.ethereal.com/) to see what type of traffic, i.e. broadcasts due to a faulty NIC, etc

Check against trojans and spyware as Netman suggested

While traffic is being generated you can run a
Nestat -an from the command prompt and see where and if there is any connection being established.

Are you running anything like Kazaa or morphious ?

While in task manager compare what processes are running. Here is some links to get you familiar with those processes:

http://www.answersthatwork.com/Tasklist_pages/tasklist.htm
http://www.blkviper.com/WIN2K/servicecfg.htm
http://www.geocities.com/greyknight17/startup.htm