Canon camera... out of these three...?

Which should I choose?

Canon s5 IS (8MP)
Canon A650 IS (12MP)
Canon SD850 IS (8MP)
Canon SD870 IS (8MP)

I heard that the s5 does a better job at movies than the others? Does anyone know if that's true? I want to take lots of movie clips of my family as well as outstanding pics.

I know the skill of the photographer has a lot to do with it - but given a choice, which of the above would be well suited for an avid photog (though not anywhere near pro!) maybe a "prosumer" :)

I know a Canon is the way to go - can someone better direct me as to which kind...

Thanks!

true, the s5 does do better movie clips. it has a higher frames per second ratio than the others. however, like many digitals, the photos will get minor digital noise with a higher iso. if you've got a very good eye for photography, you'll notice it on this camera after iso of about 200, which is slightly disappointing. most consumers dont know the difference so dont notice this small imperfection. i dont know anything about the 650is, as ive never used it. if you're going to to the 850is, you may as well got to the 870 is in my opinion. all the same features, with a newer processor and a wide angle lens (28mm equivalent). so it boils to whats most important to you --> zoom, movies, wide angle, speed...

i would consider the s5is or the 870is. i like the idea of the 870is because its small and with wide angle, but if you want more zoom than 3.8x , go for the s5 (12x zoom)

keep in mind the batteries as well.. the s5is takes 4 "AA" batteries (you'd need rechargeables) where as the 850is and 870is take lithium.

To start out, I would say no to the SD870. This camera does not have an optical viewfinder which means that in order to take a picture you have to hold the camera at arms length so you can view the LCD screen. Holding a camera in this manner is almost instant death for any thoughts of picture sharpness. Holding your camera study like this is almost impossible.
All of the other three are good choices and when handled properly will take excellent pictures for you. I personally would choose the A650 because of the higher megapixels. More megapixels means the ability to print a larger picture from your original, and the ability to do more retouching and image manipulation before image noise begins to become detrimental to your picture.

Just a thought though, you mentioned movies as a big interest. Shooting video on cameras of the point-and-shoot digital type is not the world's best idea. These cameras are designed to take pictures, and shooting video clips is only an afterthought add-on as a selling point for the cameras. If it's videos that you want you should be buying a video camera. If you want both good videos and good still pictures, you should have two cameras. If your major interest is in shooting video clips and taking a few still pictures, and making large prints is not too important to you, and your budget will only allow for one camera, you probably should buy a video camera which also takes a still pictures on a separate flash card. Many video cameras offer the still picture feature and usually do a better job with still pictures than point-and-shoot cameras do with video clips.
Just a thought, but you might want to do a little research in the video camera area before you buy anything.