Extreme out-going data - Uninvited guest?!?

[nicforrest]

I have around 15 computers on a network which is sending around 25MB/day to someone else. I don't want it to!!!
Can anyone tell me where to find a solution/program that will possibly help me in finding out which computer's doing the sending? I've cleaned all the computers of all spyware/adware/malware etc, but I'm stuck... There don't seem to be any viruses either. Does this sound like someone getting a piggyback? Or just a nasty little program I haven't found?
Any help would be greatfully appreciated!!!

 

[jimbopalmer]

I would aat least consider putting some firewall on those computers. The one I use most is mcafee's, it allows you to control which applications on your computer are starting external conversations

http://images.mcafee.com/common/screenshots/mpfp_apps_770x580.gif

I tried to remain child-like, all I acheived was childish.