re: Turning internet images into hi-res printable 8X10

Yep, for an 11x17 you're going to want minimum 1650x2550. As a general rule multiply each side by 150 for minimum resolution for decent printed quality, 200 for good, 300 for excellent. 300 dpi is considered magazine quality, so you probably don't need it. But hey, if you can find a picture you like with that kind of resolution it definitely doesn't hurt. Resizing a picture down is fine, resizing a picture up will result in lost quality (Unless it is, like GeauxColonels said, a vector. But I imagine you won't find very many of those for the types of images you are wanting).

11 * 150 = 1650
17 * 150 = 2250.