Windows XP Picture Viewer

I have always used iView for viewing JPGs and other pics. Since XP, it wants to use it’s own crappy viewer. I have tried to stop this program from running, but it is a part of Windows Explorer. My settings in iView does not help, and it is set up asthe default picture viewer.
How do I stop XP’s picture viewer from coming up? I have changed the viewer type of jpgs for iView, but this Windows XP program keeps coming up. How do I remove it?