I'll start by saying that I like the second image. The reddish color and the silhouettes make it interesting.
Now, for the fireworks photos, well, they could use some improvement. First off, shake reduction is properly named. They didn't call it "Miracle Shake Elimination" for a reason. You still need a tripod in a lot of situations. Also, both the photos you posted were shot at 0.6 sec. I'd say you need at least a two-second exposure for most fireworks. Also, the more interesting shots have more than one firework in them, which means an even longer exposure. Basically, you need to mount your camera on a tripod, set it to bulb, turn off long-exposure noise reduction (if you can), and use a wired remote. Time your shutter releases based on how you want the photo to look. Do you want to include the upward travel? Do you want the initial explosion? How many bursts do you want in one shot?
Unfortunately, you won't really have another chance to play around with it until New Year's.
In the meantime, check out my fireworks gallery:
Fireworks, July 4, 2008 - a set on Flickr
Have fun!