I've noticed that if I right click a jpg file I don't get the "set as desktop background" option in the context menu. I do for bmp and jpeg files so why not for jpg? It's not a problem as I can get around it but I'm just curious about why this should be so.
Thanks Saltgrass. I don't think there is anything particular about the jpg's to preclude them being acceptable. If I open them with Windows Picture Viewer and right click the displayed image I get the background option. I've checked Set Associations and they are the same for jpg and jpeg.
Been playing around with this as my last answer gave me some ideas. I usually have all my image formats associated with Picasa Photo Viewer. If I make Windows Photo Viewer the default program for jpg then I get the set background option in the context menu. If I set it back to Picasa then I lose it again. However both bmp and jpeg are also associated with Picasa and the both have the set background option. Interestingly jpeg also has the rotate options.