Monitoring Network Bandwidth/Usage

Hello Tech Republic Members and Staff,

I enjoy 7 articles a day received by Tech Republic, but now I am an need of a little assistance myself. I am about to install a firewall for my company. I would like to get the current network bandwidth being utilized across my T1/router now and then compare it to the bandwidth being used after I employ our firewall. I plan on blocking lots of streaming media services and websites.

What I need help with is, what free utilities/programs can I use to accomplish this task and how. I run a WindowsNT/2000 domain. I have a Cisco 2600 router (No management rights) going into a Cisco 3524XL switch. How would I gather traffic information for my router? Thank you all