A few suggestions :-
To your [Unattended] section add :-
DriverSigningPolicy = Ignore
UpdateInstalledDrivers = Yes
To your [Unattended] section remove :-
the last ; at the end of your OemPnPDriversPath entry
Prior to running sysprep, ensure that the “DevicePath” key under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion only has %SystemRoot%\Inf
Prior to running sysprep, ensure that C:\Support is not a hidden folder
Prior to running sysprep, ensure that “System” and “Administrators” have NTFS permissions to C:\Support
After mini-setup is complete, check the following entry in your registry. If everything is working correctly, then this should match with your “OemPnPDriversPath” entry.
Also, review the Setupapi.log file , located in the %SystemRoot% folder.
More info at http://support.microsoft.com/kb/302577 and http://support.microsoft.com/kb/314479
And the Deploy.chm file from the deploy.cab
Use the latest XP deployment tools…
(Note : After downloading, right click on deploy.cab, and choose “Unblock”, then OK (before extracting the cab))
Another option is to do away with using “OemPnPDriversPath” in sysprep.inf, by using a tool, spdrvscn to scan and load the required entries directly into the “DevicePath” registry key.