For movies and TV the resolution isn't that important but the lower the resolution, the cheaper the projector, the lower the quality etc...

It's important to find a balance between all the important features. Also, if you want to safeguard your investment and be able to use the projector for office work 800*600 is the absolute minimum.

It's better to get an affordable 800*600 1200Ansi Lumen projector than a 1024*768 800Ansi Lumen one, certainly for movies you don't want to have to close all the curtains all the time...