Up until a few moments ago, I was unable to preview PDF files in emails in Outlook using Windows 7 64bit.
The problem is that Adobe have not updated their installer of Adobe PDF reader to allow the correct values to be set in the registry.
However, there is a fix.
I came across this:
http://www.pretentiousname.com/adobe_pdf_x64_fix/index.html
It worked great!

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