Most digital cameras have a video output just for this purpose. Simply upload your images into the camera before the showing and then step through them once the group has gathered. The connection to the set may be either composite or S-Video. Use a special device that can store a whole presentation, such as Iomega's Fotoshow. It comes with software for creating presentations and cables to hook up to the set.
Some laptops come with video outputs.
As far as the quality of an actual image file is concerned, there's no difference between any size of memory card. If you capture a 1 MB image onto a 64 MB card and onto an 8 MB card, there will be no difference in image quality. Let's say your camera is capable of capturing a large, uncompressed image file when set at its highest resolution setting. You'd have to compress the image in order to save it to the card, and the compression will have some impact on image quality. If you were using a 64 MB card, however, you'd be able to capture several of these uncompressed, highest-quality files.