First, many thanks for the great advances in the 1'0'25 version, what a jump forward (specially for the user confort) it has been!
Getting to the point, I would like to suggest to implement a button to set JPEG Viewer the default images viewer for Windows (XP, Vista and 7). As we don't have an installer, it may be easier to buid a .bat file able to do that? A batch file that first asks what Windows version are you using and then sets JPEG Viewer as the default viewer for JPG, GIF, BMP, etc (all supported file formats).
Another way to do it could be a prompt asking if you want to do so when the program is started for the first time.
Again, many thanks for your great work.