I'm pretty sure that this is an American goldfinch. You can see the black wing with white stripe, and there's a lot of yellow on the breast, especially near the head. (It's a lot easier to see the details if you adjust the contrast of the picture a little...)
Not 100% sure it's a goldfinch, though... but it's definitely NOT a dark-eyed junco.
(Speaking of adjusting pictures, I recommend using www.picnik.com for quick-and-easy photo adjusting -- it's a free Flash-based photo editor that allows you access to the basic photo editing tools such as contrast/exposure fixing, crop, resize, etc. You can upload photos from your computer, but also can type in a URL -- which is what I did for this picture -- and it'll load the photo that way too. Just a quick and simple way to fix the bird photos a little to make it easier to see details.)