Host Discovery; hunting for Windows XP hosts

These are a couple of quick ways to do discover the OS version of your hosts:

A) Use nmap, and run the following command. 
nmap --script smb-os-discovery -p 445 10.0.0.0/24


B) Use Metasploit, and run the following commands.
use auxiliary/scanner/smb/smb_version
set rhosts 10.0.0.0/24
run

The output will display the Operating System on each of your hosts.

As a side note, you can use nbtscan for a quick host discovery
nbtscan-1.0.35.exe 10.0.0.1/24

or nmap 
nmap -sP -n 10.0.0.1/24