Question : Running a script one time

I have a script that I need to run on all the machines on my network but I need to run it one time and one time only. What's the easiest way to do that?

Answer : Running a script one time

Looking at your script, you already have something that you can use for that:
echo susid set to unique>c:\wsusfix.txt

So all you need is a simple
if exist "c:\wsusfix.txt" goto :eof
at the beginning of the script.