Thanks for the reply. From what I can see DEP is already selected for Services and Programs only.
I was on live support with a Microsoft represnetitive for over 3 hours last night and after exhausting all of the fixes around the net he elevated my support call for call back from someone else higher up tomorrow. To be honest I have little faith in actually resolving this without a clean install. I have tried registry fixes, uninstalling drivers, safe mode booting, using driver cleaning software, uninstalling specific updates, changing specific services to start automatically, tried everything. I think because it bombs out so early on in the configuration of the Service Pack that there are fundemental files that are either missing or corrupt and these are files that the Windows Repair/Check Disk and SFC are failing to pickup on.
I am left with the unfortunate possiblity of having to reinstall Windows