Attached Link: http://www.renderosity.com/viewed.ez?galleryid=1065775&Start=1&Artist=destro75&ByArtist=Yes

Yes, Lully has the best suggestion. Use a one sided square primitive, size it to fill the background, then apply the image you want to use to it. Then you will get the shadow effect on it. That's the method I used at the attached link. I don't usually like to post my gallery submissions, since it inflates traffic unfairly, but I think it appropriate here, so you can see the benefit of this method. Hope this helps!