removing jpg backgrounds from control panel display desktop box

Running XPsp3. All the pics in My Pictures were integrated there by Fast Picture Viewer I think. I'd like to eliminate all the backgrounds except those bmp images that reside in Windows in Local Disc C. Since I've uninstalled Fast Picture Viewer, the jpgs default back to my other picture program, JASC. I know how to remove internet explorer wallpaper that winds up in the desktop backgrounds box, but not all these pics from My Pictures.