Good advice so far. As already stated, you either need to crank up the ISO, or get a tripod. Increasing ISO is the least desirable of the 2 options on a point-and-shoot camera. It will increase noise to unacceptable levels. Also, higher ISO will reduce the shutter speed, so you won't get the long trails you see in good fireworks pictures. Also keep in mind the longer the exposure, the more noise you will have.
Definately get a compact tripod.
Here's an inexpensive example. This one might be TOO compact. I have
this one and it works well. Fits in my backpack and is pretty light. It's a little wobbly with a 20D and 17-40L, but it will work fine with any P&S.
Using a self timer is also a good idea (even with a tripod). Even better is getting a remote cable release for your camera. You can take more shots, and trip the shutter exactly when you want with one of these.
This is a 4 second exposure taken on a tripod with a P&S, so it had a lot of noise. I then used
Neat Image to help clean it up (Noise Ninja and Noiseware mentioned by Kelly Grannell are also good). I lost quite a bit of detail in the castle due to the noise reduction.
Just make sure to practice before you go - it's not like you have to pay for film!
grim
