I recently picked up an s400 for some underwater photography and really found it to be quite a camera. The point and shoot market has really come quite a ways, and can do almost everything a real camera can. I don't really know what the differences between the s400 and the sd400 is, but it really seems like the difference is a few milimeeters and not taking the readily available compact flash cards.

I had planned to sell my s400 and it's accompanying underwater case after my trip, but it was such a nice camera I'm tempted to keep it and sell my Casio EX-S2 instead, even though it would mean my "pocket camera" would grow quite a bit.

Matthew