Apple Quit Script

Does anyone have a script I can use to quit all the applications that are open? I have tried using the following but it doesn't seem to work.

Thanks

M

tell application "System Events" to set the visible of every process to true

set white_list to {"Finder"}

try

tell application "Finder"

set process_list to the name of every process whose visible is true

end tell

repeat with i from 1 to (number of items in process_list)

set this_process to item i of the process_list

if this_process is not in white_list then

tell application this_process

quit

end tell

end if

end repeat

on error

tell the current application to display dialog "An error has occurred!" & return & "This script will now quit" buttons {"Quit"} default button 1 with icon 0

end try

Th