As I have mentioned before here recently, I put a lot of trust in camera reviews from these two sites and have not been disappointed:
http://www.dpreview.com/
http://www.steves-digicams.com/
If you haven't already, check them for reviews of the cameras you are considering, as well as others to consider. One of those sites (I don't recall which) used to have a regularly updated "best of" list for various camera categories.
When looking at specific models, keep in mind that megapixels is just a number and more doesn't always guarantee a better picture. That is just the resolution of the sensor. When it's not matched by an equally sharp lens and low noise levels, all it will give you is a bigger file.
In general, I am biased strongly in favor of Canon. If there is a Canon that is in your price range and meets your requirements, that's where I would look first. I have been happy with every Canon camera I've ever had and they all have been passed on fully functional (except for the one I accidentally threw 10 feet and had land on concrete; and even that still worked minus the zoom).
I'm also strongly biased against Sony. Everybody I know who has had a Sony camera has had theirs break much sooner than it should. Sony can also stick their proprietary memory sticks up their ass.
Like Canon, Nikon has historically been a photographic equipment company, which I inherently trust more than electronics giants which never made still photo cameras before they turned digital. Nikon would be my second choice, as far as brand preferences go.
