I have that same camera and use Energizer Lithium batteries. They last quite a while for me. Did you turn off the start up image and other power sucking features?
I've only had it a few months and because of all the photogs here, am thinking about buying a "real" camera now.
It was the batteries that came with it that ran out. Now I'm using my favorite batteries (GP ReCyko), they're the best on the market and enironmentaly friendly too. They last a good day or two