First, as others have said, iMovie uses the pixel dimensions of 640 x 480 with a resolution of 72 dpi. You can make your images with a larger pixel dimension, but the key to remember is keep the ratio 4:3. Second, regarding pixilation, well, this is a natural phenomenon and it should not worry you too much. iMovie, along with other video editing programs such as Final Cut Express have to convert the de-interlaced computer image into an interlaced video image (or is it the other way around?). As a result, the crisp and clear computer created Photoshop image looks pixelated and blocky in the iMovie preview window. Displayed on a television monitor the image is fine. (I was going nuts because I had spent all of this time creating the perfect image in Photoshop only to have it look like pixelated crap in Final Cut Express. Someone suggested I try previewing my FCE project on a television monitor. I did so and the images looked great on the television.)