I am going to purchase a digital camera, probably by the end of the month. I have decided that I want at least 4 megapixels. I don't want to spend more than $500. Obviously, it needs to be Mac-compatible. I need advice on brands, and what features to look for. It will mostly be used for snapshots of my wife and kids, and vacation photos once or twice year. I don't know anything about photography, but occasionally I do see something that I want to photograph as kind of an "artsy" picture. A lot of the times that I wish I had a good camera involve a big, low moon and some lanscape feature. So, a camera that will take good pictures in the dark would be nice. I would also like a decent zoom. Advise, anyone?