Well, jpg is meant to be used for things like photographs. I supose high-quality artwork like Klaus' illustrations would qualify, but at 25x25 there's not a lot of detail to see anyhow. gif and png are, imo, the main image format for the net. I personally prefer png for all the reasons that people have, but since you've got to deal with people who insist on using really old (3.x or less of whatever) and horribly broken (N 4.X) browsers, you can't really use png much.