forgot to add. It also depends on what compression you use. The least compression, the larger the file.
On my old 300D, 1 Gb can fit anywhere from 250 to 350 pictures depending on the ISO and complexity of the picture. I always use Fine Large (highest resolution, least compression) JPEG.
Jilly16,
you may want to check your photo file setting because it seems like you're using medium quality instead of the best quality setting. You have a nice camera, use it to its fullest.