[K12OSN] Network Monitoring

[Barry Smoke <bsmoke bryantschools org>]

Hey guys,
I have a problem, and I would like some suggestions from everyone. 
We are a growing network, like everyone else...
and at times, when problems occur, it seems like the tools we have at 
our disposal for network monitoring are falling short of the mark.
Eric showed us Nagios, while he was here for our Hot Springs Tech 
Conference..., but from what I can tell, it is involved to set up(which 
is fine...I can handle that), but also it looked to be specific to 
servers that you set up.  I am looking for more of a network wide 
traffic monitoring/control setup.  I want to look at my screen, and know 
what host/ip is sucking up bandwidth currently, so I can react, and shut 
them off..

I want to have this monitoring program tell me what traffic I'm looking 
at, meaning, if it is kazaa I'm seeing, I want it to label the traffic 
kazaa, or probable kazaa, winmx, morpheus, etc..
I want this program to also have a traffic meter, showing a throttle of 
traffic going to our samba server...(let's say we have a 4 gig trunk, 
have a visual graph showing realtime usage of that 4 gig pipe)
intrusion detection...

ideally, this would be a drop in replacement for our firewall, and I can 
put 2 in...
one between our switches, and our router
the other between our internal lan, and our proxy
I can point and click to turn off kazaa traffic, or throttle web down to 
only take up 75% of our internet pipe, so our internal state telnet 
connection
will always work(or allow it to be prioritized )

is it time to take a project, like smoothwall(or a custom knoppix cd), 
and branch it, to do this stuff by combining functionality of other 
projects together into one ultimate network traffic control box?

what is everyone else doing...?