Network Mapper

[Lucas Peet]

Does anyone know of a utility that's a sort of IP 
Scanner/Traceroute/Visual utility that can scan a block of IP addresses, 
traceroute them, and visually display a map of a network?  (Like 'Here's 
the internet, connected to this router, behind this PIX, to this switch, 
etc...)

I need to map out a network here, and (in the end) convert it to a 
Visio/OO.oDraw file, and would rather not have to physically trace wires 
and map it out by hand.

-Lucas