Fir still images I never have any problem with File > Import > Background Picture.  I even think you can use a GIF, or AVI there(may need to do so from the material room though)  I know what size my scene is a, and then crop my image to match ahead of time, of coarse; but I think this displays the background image best.

If it is a prop your interested in, I suggest you look toward spheres.  You'll be surprised how well maps can be created for Sky Domes.