Windows Picture and Fax Viewer is a view, not an app.
From O'Reilly, "The Windows Picture and Fax Viewer isn’t a standalone application in the traditional sense, but rather a simple viewer window. When Windows XP is first installed, it is the default viewer for [emf, gif, jpeg, bmp, png, tif, wmf]"
And from CNET, "The command to run Windows Picture and Fax viewer is: rundll32.exe C:\WINDOWS\System32\shimgvw.dll ImageView_Fullscreen path-to-picture "