Hi! As i said in a previous post about film, i am in the photo developing buisness, and 800 speed should be ok, but...............
If you want really great fireworks photos, i'd recommend 1000 speed or better.It can be hard to find (i.e. not at the grocery store, try a camera shop) but it will take photos that are so crisp and clear that it looks as if they were still pictures and not motion.
This is the film that professional photographers use to shoot races, fireworks,etc...
A word of caution though.Not all cameras can take 1000 speed film, especially point and shoot auto focus cameras.Check the manufacturer before you buy.
If you are a real photo buff it might be worth the while to invest in a good SLR camera.( the huge ones you see foregin tourists carry). They aren't cheap but the photos are the best.Hope this helps,
Sherrie