Suggestions For Multi-Interface Bandwidth Monitoring?

[ElectroPulse]

Hello, all!

We have a very, very slow internet connection (272kbps down, and not entirely sure what the up is… Somewhere around 150-200kbps) on a school campus, so I am looking for a package that can:

Required:
1. Monitor bandwidth usage per user
2. Can monitor multiple interfaces (hopefully 5, as we have 5 LAN interfaces right now, due to VLANs)

Would like:
1. 5- or 10-minute average usage per IP (or 5- or 10-minute download amount)
2. Display 24-hour, 48-hour 1-week, and 1-month download amounts

Basically, I would like it for two purposes: 1. If the internet is being slow, I would like to be able to determine whether someone is downloading files or if everyone is just online browsing. 2. To be able to identify bandwidth hogs on the network.

I am asking here because it takes quite a long time to download packages, and it would save a tremendous amount of time to get the first one during the first go, rather than downloading every bandwidth monitoring program (I've tried 2-3 in the past... None worked for what I need) to try them each out.

Thanks!
ElectroPulse