If you already own a digital camera, you know you paid a lot for the camera compared to film cameras you owned before. But you perhaps justified the upfront cost due to the money you'd save buying film.
You probably enjoy being able to take many more pictures without the burden of having that film developed. You enjoy the instant gratification of seeing the picture without having to wait a week for it to come back.
There are a lot of advantages to digital over film, it's true. But you go through a lot of batteries? And the one(s) that came with your camera lasted how long? One day?
Here's what I did. I bought a couple of battery chargers. My favorite is the 15 minute charger. I can carry the charger with me if I plan to take a lot of pictures. I have the quick charge batteries because when I'm needing to take a lot of pictures, I can't wait 8 hours for a charge.
The batteries are rated NiMH 2000mAh and the package said they were good for cameras and other high energy users such as games. The higher the number is, the longer the battery life and the better for your camera. The 8 hour charge batteries will give you more charges and last longer in camera, but you have to consider your needs.
Think about the old days when they came out with those alkiline batteries and you paid the extra money because they lasted more than a day. This is similar. Go for the higher NiMH rating and you'll notice a big difference, too.
Your camera needs more energy to perform at its highest level. Whether you choose to buy disposable or rechargeable is up to you.