If it still a problem for someone, I'll put my 50c how we managed to fix this:
We have a list of unattended files in [installation_directory]\Altiris\Notification Server\NSCap\bin\Win32\X86\Deployment\SOI\AnswerFile
When I did the change as Joel mentioned:
<OOBE>
...
<HideWirelessSetupInOOBE>true</HideWirelessSetupInOOBE>
...
</OOBE>
it didn't appy, as the changes are not picked up by the unattend.xml file. We get this approved by open the unnatend.xml file from the command prompt when the task been applied to the laptop. It should be in the root of the X:\ drive.
I tried a lot of things, even we created a new package of the OS deployment (which is picked up the new string successfully).
So, going to the fix :) the fix was easy:
We have enabled the "Default configuration" in our Windows Deploiment task, saved changes, tested - working (string appeared in the unattend file), then switched back to the "Use inventory data to reconfigure computer" configuration, saved settings, tested - and now it picked up the string.
So, for me, it looks like a "bug", someone could say that it is a metadata cache, but it fixed our issue.
Hope that helps someone, or might be me in the future :)