Yesterday looking out the kitchen window we had another hawk...this one larger than the one the other day. So, after some investigations we have decided the one the other day was a Sharp-shinned and the larger one was a Coopers Hawk. That's our story and we are sticking to it! Cooper's Hawk and Sharp-shinned Hawk
Here is a great place to learn the differences... http://www.birds.cornell.edu/pfw/AboutBirdsandFeeding/accipiterIDtable.htm
No photos of the Cooper's Hawk, he was too fast.