The number of pixels does not count. There are a lot of other important factors - lense quality, sensor quality, image processing etc.
Example: the 6MP $800 Canon EOS 300D (Digital Rebel) is BETTER, BETTER, BETTER than the 8MP $1200 SONY 828. There are a lot of other examples (can be seen at
www.dpreview.com
Consider to buy a camera with a CMOS sensor. This type of sensor delivers silky-smooth images without any sign of noise even at ISO-400.
My advice: Canon 300D. I use one - it's a great camera, even with the dirty cheap EF-S 18-55 lens.