Hi,
I have a 4 megapixel Canon S40 that I've had good results with for fireworks shots. It's about 4 years old, and is speedy enough, though probably slow by current standards. I've got some shots I've taken with it (fireworks included), and bunch more firework specific tips on my site at: Disney.rocket9.net .
I've used multiple Canon Powershot and G-series camera's and been very happy with all of them.
Bernie