This caused me some serious headache a few months ago (at another customer).I investigated the problem and found the cause of the problem.I think you have a problem not with the driver or sysprep but with BIOS settings - Win XP does NOT support SATA AHCI.
Since the machine is provisioned with a Windows 7 installation out-of-the-box it is easy to determine the NIC installed.
In this case a To determine if the driver is already present in the driver repository of the Win PE image I need the Vendor and Device ID.
The device contains the ‘RTL8167’chipset according to the PCI database.
Now we know the NIC (and chipset) we can find a driver for Win PE 2.1.
This package provides the Dell Win PE 5.0 Driver CAB Pack and is supported on Latitude, Optiplex and Precision models that are running the running following Windows Operating Systems: XP, Vista (32/64-bit) and Windows 7 (32/64-bit).