Management Software

Howdy.

I’m a consultant at a small non-profit (4 remote sites, 1 central office, about 55 desktops and 5 servers) on the East Coast. I am seeing some high bandwidth utilitzation (as evidenced by poor internet performance). Logs and graph in my router console indicate a lot of activity. I’m wondering if there’s a good utility anyone can recommend a good 3rd party management tool for monitoring network traffic. Given our budget constraints, it needs to be something cheap (less than $100, if possible), and easily configured (can’t spend a lot of time setting it up, in the middle of many projects).

Any thoughts?