I need to buy two inexpensive projectors for my school (grades 7-12, public charter school). The projectors will travel between classrooms so they need to be durable. Lighting conditions will be hard to predict. Ease of use is important as well, but last on the high priority list. They will mostly be used for hooking up to a computer but I could see using them for DVD/VHS movies every now and then too. Any help would be great!