alpha rom works on dvd movie format afaik..
so think if the exe's you have are really needed, or could you do it better/another way using dvd menus...
drm (digital rights managment) works on licenses, where if the person does not have the license to view the movie... they cant view it, you're using avi format, so you can put drm in it
http://www.microsoft.com/windows/win...s/drm/faq.aspx
£15 on each set might be too low though, as for the usb dongles, all they can really do is provide code protection - so again, only protecting exe's, memory isnt really a matter here...
realistically i think you have an issue here on cost / profit vs. cost of applying protection, with such a low volume, commercial protection might be 'out of your league'