To conclude this issue, we ended up using WDS to launch a PE environment based on 7/2008 R2 (cannot remember which). This then runs the script I've already posted to format the partition etc but instead launches the winnt32.exe to start the setup, pointing to an unattend file rather than uncompressing a WIM. So, we boot a computer, press F12 to PXE boot, select Windows XP setup, this loads PE, formats and partitions and sets active the drives, maps a network share, triggers the setup to copy files thought the GUI mode from the network share (I assume its making a local source) and then reboots. Windows XP setup starts again at text mode setup as though we've booted off of a CD. The drivers for all types of desktops and some laptops are integrated. I've even merged two textmode driver packs for Intel and AMD chipsets so that both types of SATA and SCSI controllers are supported (we have some Dells have a SATA mode whose default is a "SCSI-Emulation" instead of AHCI in the BIOS). Some "prerequisite" hot fixes are slipstreamed to the network copy of the XP setup files to save a number of Windows Update related reboots. A "first run" script installs .NET Frameworks 3.5 and 4 because there are some other prerequisite fixes needed before these appear via WSUS. The first run scripts also re-names the computer based on the asset tag in the BIOS, deletes the entry from AD based on the XP given name and re-creates itself with the new name in AD before auto-rebooted. All in all a very successful process if I dont mind saying so myself.