windows 7 - Excel document opens in IE 64, not in IE 32

Whenever I click on a hyperlink to a scrip that outputs an Excel 8 document, I get a prompt from IE to open the file or save-as. If I click open in IE 32 bit, the document opens in Excel (which is what I want). If I click open in the 64 bit version of IE, the document opens in the browser.

How can I make both versions of IE open in Excel? I am using IE8 on Windows 7 64 bit.