Thanks for the accurate info, I pulled the number 90 dpi from the cobwebs.

I notice also that Toms images are interlaced. (if you have a slow enough computer, you can see them load in layers)

I think that the images are limited to JPG, GIF or BMP. (never tried TIFF or some others that might) Considering how large BMPs are, it's down to what you said about GIFs or JPG, and GIF graphics are better while a compressed JPG for pictures is better.