When I test the functionality of the Boot CD WinPE I cannot see whether it failed to Boot and the system defaulted to the version installed within C:\Boot\???
On XP using v4.2 I only knew the Boot CD had failed because when the screen said Windows was loading files the CD light was not flashing. I recreated a new ISO and found the new version was 3.1 MB larger because this included a file that some-how never got included in the first attempt. This version booted clean.
Had I been less cautious/suspicious I would have enjoyed a false sense of security until reality struck.
It would be good if the "loading files" message said what it was loading files from, and also if the main WinPE menu stated whether it came from CD or HDD. (I have been known to boot from CD and immediately retreat to the kitchen for coffee/snacks, and not return to the PC until it has finished loading and is ready for action.)