I am using a series of .png images (from green screen footage) with alpha channels. However, when I try to import image(s) as plane(s) in a rendered scene, the image is blurry with anti-aliasing off. If I turn on anti-aliasing, then I get a frame artifact around the image plane.
Also, is there a way to setup the plane so objects behind transparent parts of the image can be seen? I am using Blender Internal and an AMD Radeon HD 5770 graphics card.