it does not matter what OS is on the device - if you boot from an OS image, that's the one which will be used - not the files on the disk of the host device.
But, if you are using a Surface Pro - shouldn't you be using the uEFI version of EETech, not the BIOS version?
Thanks for the link. I have Win PE v4 and I'll go through the EETech config for it in the near future.
Thanks. That did the trick for the Surface.