What are some good tools to look into for measuring network performance? 
I'm working in a heterogeneous environment consisting of a router, switch, 
NetBSD/Linux, and Windows machines (XP/Win98).

The equipment is nothing fancy (it is my home setup), so don't expect a 
SNMP interface on my router or switch.

I just need to know where to start looking since I am a networking ignoramus.

--

Brian