Many consumers buy a camera based on the number of megapixels it has. Today, doing that is generally a mistake.

Megapixels only matter to a point, in fact higher megapixels will often result in more noise in an image. (Noise is ugly "speckles" of color in an image usually most noticeable in the darker portions of an image, but they can also be seen in lighter portions of an image if it is bad enough.)

A 10 megapixel point and shoot camera will often produce poorer images when compared to say, a 6 megapixel. The reason for this is that the sensor makers tend to cram more pixels closer together on the the sensor to get a higher megapixel count. This results in more "noise" in the images and very often poorer images.

Digital SLR's have very large sensors when compared to a consumer point-and-shoot camera. In this case a 6 megapixel DSLR will produce superior images than a 10 megapixel point-and-shoot.

For most people, a 6-8 megapixel will be more than enough. It will produce good 8x10 prints. In addition you will be able to put more images on the card, and the camera will tend to less expensive. Years ago megapixels mattered but that is much less true now and has become more of a marketing pitch than anything else.

The one place where more megapixels can be an advantage is if you want to crop an image--in this case, more IS better. But even cropping a 5 mexapixel image will usually result in a more than acceptable image.

Before moving up to a DSLR, I had a 5 megapixel Olympus and the image quality from it of an 8x10 photo was fine.

As far as Sony vs Canon goes, Canon has been making cameras far longer than Sony and has much more experience in this area. Between the two, the Canon will probably be better. The Sony may be okay, but generally the Canons are considered superior.

Just read the reviews for the cameras. But don't read them at amazon or sites like that, instead go to a dedicated digital camera site such as DPREVIEW, KENROCKWELL or others. I've found consumer review sites to be iffy at best. The dedicated camera sites are generally much more accurate.

Happy shooting.