A570 IS vs A590 IS?

I have a Nikon DSLR, which is great, but I need a compact camera to take everywhere.
I am looking at the Canon A570 and A590 cameras. So far I see that the A590 has 1 more megapixel and is built better, but the A570 has a better movie mode and it supports CHDK.
Anything else I'm missing? Anyone's opinion would be appreciated.

I have the A570IS, and have enjoyed it. I've never had any difficulty with the build quality (my poor camera is often thrown into my purse at the last moment, is not kept in a case. I did drop it once, on carpeting, and it still works!). The image quality is wonderful, and it has some manual controls so your not stuck with only using auto mode. I am, however looking to upgrade because I need more zoom then 4x, and I do find the camera a bit slow from shot to shot. Other than the speed and wanting more zoom, I think the A570 is an excellent camera.