I have read some technet blogs saying syspreping isnt required anymore. Personally i dont put too much faith in any technet blogs. I'm sure in most cases this could be true, but i have ran into issues that have been solved by syspreping the images. If this is really true, why did Windows 7 ship with a sysprep tool pre-installed? Syspreping will also alert you to problems (not literately, but by failing) long before you roll your image out. IMHO, spend the extra 10minutes and save your self some time. FOG does not alter any UUID information.