at your price range, anything you're looking at with 1.3ghz has to be dual-core. Also, there are other factors that make the Atom computers slower, such as the fact that most of them only come with 1gb of memory. Any laptop you get would come with at least 3-4gb.
what kind of photo editing are you talking about? serious photoshopping or casual cropping and editing? For serious photoshopping I would make sure the notebook has an integrated ATI/NVIDIA card and not just an intel chip.
I like the new i5-430M laptops. They're only dual core but they have the integrated memory controller of the other i5/i7s, and if you catch them on sale you can get one for $600-650US. (I'm not a financier but that should be about 1000euros no?)