I bought the Canon S400 a couple of months ago and I'm very happy with it. I carry it with me everywhere.
The A70 and A80 are really nice cameras but I thought too bulky. The S400 felt comfortable in my hands and its so small I carry in my pocket when I hike and put in my bike bag when I ride.
It's basically a point and shoot camera but has enough features to keep me happy.
The only action pictures I've taken were kids dancing at school but I was able to get pictures of them without being blurred.
I ordered my camera online from NewEgg.com.
Check out the Canon forum at
www.dpreview.com
Remember, you will also need an extra battery, an extra memory card, a carrying case, and possibly a card reader. However, you can get those items as you see a need for them.
If you order online be careful. Low ball prices could mean reconditioned or grey market, which affects warranty.
Good luck with your purchase.
Kathi