Multiple web sites bandwidth utilization

Hi folks,

We have a clustered (MSCS - failover) web server running W2k3+IIS6 hosting
almost 120 web sites.

Last week we´ve been surprised by a single web site consuming almost 17 Mbps
of our 60Mbps internet bandwidth.
To avoid this kind of surprise, we´ve enabled bandwidth trottling for every
web site hosted in this server, we´ve set the maximum bandwidth utilization
to 1024 Kbps (default value).

Now, after this mes, several broken SLA etc... I´m trying to monitor
individual web site bandwidth utilization. My question is ...How can I
monitor this? is there any performance counter that will let me measure
bandwidth utilization of my web sites (individually)??

Any help will be appreciated ...

Thanks in advance ,

Ricardo Coelho