And to make matters worse...
All other things being equal, a larger megapixel camera tends to be worse in low-light than a lower megapixel camera. That's because there is less light falling on each individual sensor. This tends to cause more noise.
But, as cameras get newer, they tend to have improved noise reduction routines, so it usually balances out. (And a camera with a larger lens will produce MUCH better low-light results, as the bigger lens lets more light in.)
For example, I 'replaced' a 2 megapixel, large lens Sony DSC-F505 with a 5 megapixel, micro lens Sony DSC-T1. In bright sunlight, the T1 produces better pictures. In even a moderately well-lit house at night, the F505 produces better pictures. And outdoors on cloudy days or at dusk, the F505 just blows away the T1. (While the T1 is capturing more data, it's so grainy that it's not worth printing, even if I could blow it up larger. The F505 may not be able to blow it up as big, but at least it's worth printing.)
This is why in Sony's newest 10.3 megapixel R1, they use both a physically larger imaging sensor and a large lens. This way, they get about as much light per individual sensor as a smaller megapixel camera.
I say 'replaced' because even though I bought the T1 with the intent to get rid of the F505, I've kept the 505 around for low light use, even though its LCD screen is cracked and unusable.