Saving an image to your own hard drive for personal and PRIVATE use/viewing is absolutely fair use. So long as they're not redistributing or sharing the image (or a derivative of it), they're fine. Assuming that anyone/everyone who downloads an image must have some sort of evil intentions is just as wrong as assuming that everyone who uses right-click is trying to download the image to begin with. :-)

"When a man gives his opinion, he's a man. When a woman gives her opinion, she's a bitch." - Bette Davis