go check the url
http://www.dcresource.com/
http://www.dpreview.com/
i prefer Nikon rather than Cannon because of the picture quality. (BTW, Cannon is not bad at all).
speaking of the size, i think it is up to individual. certainly you do not need some big ones like the professionals'. but if the size is too compact, it is not easy to hold it still while shooting. try some
at the store and feel it.
good luck!