Lots of utilities default to JPEGView as a JPEG viewer because for a long time, JPEGView was the only decent JPEG viewer for the mac. Some of these programs are nice and allow you to change viewer to Jade. Others are not. To make life easier for Jade users, JVWR->Jade is an application that sits in JPEGView's place and redirects all images to Jade. JVWR->Jade will have problems if JPEGView is installed in your system (its tough to pretend you're JPEGView when the real thing is sitting right next to ya).
