As Pixieone says, you only need high amount of mega pixels if you want to enlarge the picture a 3megapixel is more than adequate for anything that is not going to bigger than normal photo size. However that said it is good to have the option. Although entry level digital cameras have about 6megapixels anyway.
What is much more important is the quality of the lens. You can have a 10megapixel camera with a rubbish lens and just get not so good pictures that do not deteriorate in quality if you enlarge them - but they are still not so good.
I would be worrying less about the pixels and go for a good quality brand name such as Cannon or Olympus and buy the best you can afford within their range.
I think I have waffled somewhat