Q:

Open TFS Work Item Attachment in Image Viewer not Web Browser

Is there a way to open an attachment for a TFS work item by double clicking on it (or rather just opening it from the IDE) in your computer's default image viewer, rather than opening it in a web browser?  I'd love to be able to change this setting (if it is a setting). 
Edit: after reviewing Kate Gregory's response, I looked into this option and realized that the trouble is that VS is launching a url (a handler file to respond with the attachment), which results in the default web browser being launched.  A potential work around i'm considering is writing a custom mapper for all web based calls (as in, when going to start->run and enter a URL) that the mapper would determine what kind of call it is (TFS, etc) and use an appropriate program, based on the MIME type responded with, with a second phase to be incorporate this as a VS add-in. 

A:

I'm reasonably sure VS just uses your default program.  Word for .doc files, IE for .htm files, and (in your case I bet) IE for .jpg files.  Try changing the default program you're using in Windows and see what happens.