its really quite simple to get the screengrabber app to work, just download the one of sky and unzip it, this gives you 4 folders. the CONTENTS of the folder called debug_e goes on your xbox e drive, the CONTENTS of debug_c goes on your c drive. then the WHOLE FOLDER called debug mode goes on your xbox e drive, in the apps section. now, reboot your xbox and go to apps and debug mode will be there, select it, then it will ask for a name, anything will do (?)
you will then find yourself in the debug menu, use settings to set up a ip address for debug mode(NOT the same as your default dashboard, i just changed the last digit by one) now simply launch unleashx (included) and boot up Forza!!!!
now, on your pc open the fourth folder called XIG2 and run it, enter the ip address of your debug mode in the bottom left corner, then click settings and create a folder to store your screenshots in.
now simply click "capture" and the app will take a screenshot of your xbox!!!
if nothing happens at all, that means your ip settings are wrong. (it took me a couple of attempts to get it right)
once you've got it set up correctly its a doddle to use, as all the settings get saved, and theres no messing about! B)