ever since i got ADSL and set up a small four-computer home lan, my router has been catching scans from computers...destined for ports 137-139. At first I reported them to my ISP...but I never got a response so I assumed they did nothing so I just ignore it now.

As long as your firewall is catching...and stopping (duhh) it, then I wouldn't worry about it, but that's just me.