[wplug] what os is running?

[Emilio Xavier Esposito]

Hi
This is going to sound a bit odd, but I want to find out what OS the 
machines on my network are running without going to each machine.  Is 
there a way to "probe" each machine without being overly intrusive? 
This is being done to compile statistics and nothing more.  We are 
curious what OS (Linux, *nix, Mac, Windows) is running and the number. 
I'm aware of <www.netcraft.com> but I'm looking for something that will 
run in batch-mode.
Thanks
Emilio