Works fine...
Did a clean install with my slipstreamed XP SP3 today on a Q6600 and it all went swimmingly and works fine
The only updates available from Windows Update afterwards were the latest Malicious Software Tool, IE7 and WMP11 - so its been a worthwhile exercise.
I may now find an update pack and slipstream IE7 and WMP11 into this now for a fully up-to-date version.
I then later installed Vista Ultimate SP1 64bit as a dual boot and that went fine too