Hi Rolan and Tweeters,
As several others have correctly pointed out, it is a Rough-legged Hawk. However, as the iris color is yellow, it is an immature, not an adult, bird. The adults will have a dark iris. Red-tailed Hawks are the same.
For those of you interested in Rough-leg plumages, check out the recent (2005) "Basic II and Basic III plumages of Rough-legged Hawks" by Bill Clark and Pete Bloom, Journal of Field Ornithology 76(1):83-89.

Bud Anderson
Falcon Research Group
Box 248
Bow, WA 98232
(360) 757-1911
bud at frg.org