Typing "dual monitors dual wallpapers" on Google you'll get lots of large
elongated views to use as 'paper. [or use Irfanview, etc. to make your own]
Also, Irfanview has [or at least Had] a "Panorama" effect that puts two or
more images together. Select two pictures and resize and align them as a
panoramic 'paper so one (half of the) pic comes out on each screen.
