So... I had just about settled on the Powershot A640 (thanks in no small measure to Gordon's review), when I came across the Powershot A570 IS and I'm wondering if it's worth considering.
As far as I can tell, the main differences are that the 570 has image stabilization and Digic III. Well, that and the 570 runs on two AAs to the 640's 4, and lacks the 640's flip-and-turn screen (I was rather looking foward to that feature).
I guess my first questions are, how important are Digic III and IS to overall photo quality and camera performance?
I'm basically looking for a nice "little" camera to keep with me for spontaneous shots (I do have two wee children, so I'd certainly be taking shots of them both indoors and out, but I also enjoy taking the random "art shot" on occasion, if something strikes my fancy). This may also be a crucial point-- I believe it's only a matter of time before my partner succumbs to the Nikon D80, so we'd have that for more serious shooting... but I think we'd both enjoy using a compact with some manual controls (hence my attraction to the 640... although I think the 570 affords a fair amount of manual control as well).
I will stop rambling now, but would very much appreciate any of your thoughts on the A570 (or any of the other compacts out there, if you would like to confound me further

)