I am looking for a protector for my notebook computer. I need to use it during the daytime in a classroom for ppt and at night to show movies. It would be helpful if it would be able to hook up to mp4 players, xbox, etc but that is not the most important. The size of the projected image is also not very important. What is most important is being able to use it in situations that are not optimized for projectors, i.e. pitch black. Has anyone personally used or seen this Optoma projector in action? I like many aspects about it could not find any specs on how many lumens it puts out. My classroom is on the 5th floor of the building and has no curtains. the windows face the north and run the whole length (about 40ft) of the classroom.

Any help here? If the projected image size is only 60" does a projector need to have so man lumens?