This fresh tip comes courtesy of ZuneBoards' ACE who reminds us there's more than one way to enjoy the Now Playing area. In addition to the default mosaic of your album art, you can also set a slideshow of your own photos to play while you're rocking out.
It's easy enough to do; go to the Pictures tab of your Collection, and right-click the folder or picture you want to start. Click play slideshow and you'll be transfered to the Now Playing screen which should be filled with your pictures. You can alternate between controls for Music or Slideshow by clicking the button toggle.
P.S. ACE: I get the bug too (Vista RTM & SP1--haven't tried XP), but only from photos in the Public user folder. My personal photos load fine.