Network monitoring software?

Hi all,

I'm looking for a simple-to-use network monitoring package that'll run on my Mac (or run on a server and display on my Mac), and show me the health/status of all the ports on my switches an' stuff. And possibly show me which ports are generating high traffic.

I've tried Intermapper and didn't like it; I've tried Lithium and liked the *look* of it a lot, but no matter how I tried to install/configure it, it just killed the performance of my server (MacMini 16GB).

I'd be grateful fro any other recommendations!

Cheers,

Al