Help with a startup script group policy

Hello Experts,

I have been asked to uninstall all old versions of Adobe Flash and install the newest version on several hundred PCs.  I’ve read about doing this with a GPO or through SCCM (we use SCCM 2007), but I have not been successful with either of these options.  The cleanest way I have found to do this is using the following script (named AdobeFlashInstall.cmd):

taskkill /f /t /im iexplore.exe
pushd "\\netapp3140a\sccmdata$\sources\apps\AdobeFlashPlayer"
Uninstall_flash_player.exe -uninstall -force
Install_flash_player_11_active_x.msi /QB!
Popd

My question to you is what would be the best way to run this script on the remote PCs.  My initial thought was to configure a startup script GPO.  I did the following steps in setting this GPO up”

Open Group Policy Manager
Created a new group policy object named FlashInstall
Edited the GPO as follows:
      Computer Configuration-Policies-Windows Settings-Scripts-Startup
      Added the following script:
      \\netapp3140a\sccmdata$\sources\apps\AdobeFlashPlayer\AdobeFlashInstall.cmd
Linked the GPO to my test OU
Ran a gpupdate on my PC (which is in the test OU)
Rebooted.

After the reboot my old Flash was still on the PC and the new one was not installed.  Can anyone see what I’m doing wrong?  Is there a good way of doing this with SCCM?

Thanks,
Nick