Dunno if you got it figured out but I might I suggest a program called UltraMon ... It is awesome for a dual monitor setup.. I have been using it for a few years now and its not right anymore without it... it gives you an extra task bar on your secondary monitor and all kinds of nice things... Also you can set a diff background on each monitor...
oh btw the best way to have a continuous desktop image is to find or make images that are 2x the width of your desktop so it does not have to stretch... Panaramic landscapes look awesome..

... so instead of a 1024x768 image you would want a 2048x768 image....