How many photos can a 256-MB memory card hold?

The number of photos that can be held depends entirely upon what quality you wish to shoot the pictures at. A 5 megapixel camera, at maximum resolution, probably won't hold many photos. (25-30) As the resolution increases, the number of photos that can be held decreases exponentially. At a lower quality (say 640 by 480) you can hold between 1000 and 3000 photos on a 256 mb camera, depending upon the compression.