each user startup folder help

[evilvoice]

Im not sure how to do this...Im still trying to work it out in my mind of a way to do this, but I figured maybe someone has already figured this out..

How do you get a file to start for each user profile, but then once it has runonce for that user, it will no longer run again? This is to do add a reg setting for msn and yahoo since the reg setting to make them start on startup is per user and I may have anywhere from 3-500 users (500 is a little high, but I could have a lot of users) and I want to make it to where these messengers dont start. I will be editing this post to brainstorm...but im posting now just in case someone has a way to do this...

This is the batch file, which I think is done now, just need to find out where to stick it

@ECHO OFFfor /F "skip=4 tokens=3" %%i in ('reg query HKCU\Software\Customization /v Done') do set yp=%%iif defined yp (    exit) ELSE (    reg add HKCU\Software\Yahoo\Pager /v "launch on startup" /t REG_DWORD /d 0 /f    reg add HKCU\Software\Yahoo\Pager /v "tour" /t REG_DWORD /d 0 /f    reg add HKCU\Software\Microsoft\Windows\CurrentVersion\Run /v MSNMsgr /t REG_SZ /d "" /f    reg add HKCU\Software\Customization /v Done /t REG_SZ /d 1 /f)exit

Now, where to stick this so that it will run on every user when they login. I could add it to startup folder where it will run....but I need this to run before msn and yahoo are started, and Im not sure if the startup folder just starts everything at once or if there is a pecking order.

[evilvoice]

updated batch file...Also does anyone know of somewhere that I can add this file to run before anything starts? Maybe not anything, but I want it to run before the things in "Run" reg key and before the startup folder can be processed...I think the only thing that runs before any of those is runonceex...but any suggestions would be greatly appreciated.