Check which IP address your host gets when you plug it in the network. For example, if it is something like 192.168.xxx.xxx, you can use Nmap or any other tools stated above to look after live hosts or at least hosts that respond to ICMP. By doing that you should discovery every responsive IP address in the range of 192.168.
If you are in a at least a decent corporate network you shouldn't be able to connect to others subnets from a regular workstation and by that I mean you won't reach different networks like 10.xxx.xxx.xxx or something like that.
A quick Google search returns the following command to use in a CMD on Windows systems:
FOR /L %i IN (1,1,254) DO ping -a -n 1 192.168.10.%i | FIND /i "Reply">>c:\ipaddresses.txt
This will try to ping all addresses contained in 192.168.10.1-254, resolve their names and write it down on a .txt file at "c:". "%i" is the variable