I have a mac mini with w7HP running two monitors. When I run a slideshow with Windows Photo Viewer, I can't use "windows shift left arrow" to move it to the second monitor. This key combo works fine when the slide show is not running, and it is just viewing photos normally with the menu bar on top and the few buttons on the bottom (left, right, magnify, rotate, etc). This key combo also works fine with other programs like firefox, explorer windows, etc.
If this is any hint at all, I found out that this key combo didn't work at all unless I unchecked the "prevent windows from being automatically arranged when moved to the edge of the screen" option in Ease of Access center -> Make the mouse easier to use"
Edit: OK, I found out that the reason it wouldn't work is that the second monitor is rotated relative to the first (it is turned sideways). The only way I can get it to work is to rotate the second monitor back to normal, start the slideshow, move it to the second window, and then rotate that window back again. Surely there must be an easier way?