Megapixels is simply the size of the image. Some people think it means the quality of the image, but it does not. However, with more megapixels you can print bigger images without having to strech and thereby lose quality.
With 5 megapixels, I believe you can print up to about an 8x10 image. Don't get sucked into the trap thinking that more megapixels equals a better image. If you won't be priting large images, then 5 megapixels is enough. What does determine the image quality is the quality of the lens.
Check out the site
www.dpreview.com for a lot of good, in-depth reviews on any camera you're considering.