I have a web application that needs to open Excel files embedded into the web page. However, Internet Explorer (9 in this case, but the same goes for 8) only gives me the option to save or open the file and when I choose open, the file is opened within a new Excel window.

As far as I understand, opening files within IE should be the default behaviour, but for some reason that seems to have been altered in my installation and I can't seem to find a way to fix that. I'm running Windows 7, so there's no File Types tab under Folder Options in Windows Explorer.

Any ideas on how to fix this?

I can change the file association but this will open all excel files in IE and I only want ones that are embedded in the web page to open in the browser.