Windows 7: Remote Shutdown advanced Batch Job

Hi!
I've created a batch file on my machine that will shutdown all the computers on my network. Here is my coding.
@echo off
echo Would you like to shut down all the computers on the network
set /p choice=(Yes or No)
if '%choice%'=='Yes' goto :Yes
if '%choice%'=='yes' goto :Yes
if '%choice%'=='No' goto :No
if '%choice%'=='no' goto :No

:yes
shutdown -s -t 20 -m \\computername
shutdown -s -t 20 -m \\computername
shutdown -s -t 20 -m \\computername
shutdown -s -t 20 -m \\computername
shutdown -s -t 20 -m \\computername
:no
echo Computer shutdown disabled
@pause




I would like to know if there is a way that I could add code that would tell me that if a computer is not responding it would say it is shut down.