I have been using
this free software for a couple of weeks now to monitor all traffic on my router since i learned of VM capping bandwidth.
Its a pain to set up and is a bit flakey but i basically run it on my server 24/7 and it monitors VM limited zones.
when i reach 80% of the allowed cap it emails me, which i get on my main computer and i can then log into the server with remote desktop connection and halt my downloads and/or uploads til that time zone moves.
what I have also learned during this time is that VM dont give me 20mbit. All tests i conduct show it at between 15 and 17mbit with a 600k upload at best.
I've also seen my bandwidth drop down to 50% during the night for no apparent reason and then go back up in the morning.
when i have been capped it has been much more than shown on their charts - often to the point of 56k modem speeds and it gradulally builds up speed over several hours.
I dont belive they run a fair system as they describe and I will continue to suck as much bandwidth as possible - even if i dont want anything