It's simple: if you get for less than $400 what a camera of $1500 offers, then there must be something wrong with the quality.
My idea:
1/ AA batteries are handier and less expensive that NiCd or whatever. You always need at least two sets.
2/ megapixels does say nothing about quality but about printable size. The sensitivity of the sensor is much more important. Example: no or not too much noise at 400ISO and up.
3/ quality of the lens and its opening. With f:4 and up, you'll have to use flash a lot once you're out of sunlight. Something I dislike. I never use a flash.
apart from steves digicams, there is also
www.dpreview.com
you can also go to your local dealer and try some cameras out.