A while back I wrote a post  about a nice, free Outlook 2007 original author  of the free add-in that provided this functionality, has updated his entry removing the download, because Adobe has apparently included this functionality in their Adobe Reader 8.1 release. In memory of the useful plugin, I’ll say: So long, and thanks for all the fish! (At least it has a happy ending.)
Update in April 2008: If you don’t like the Adobe Reader software, try using Foxit Reader, a free alternative that loads much more quickly. Outlook 2007 original post here about Outlook 2007 PDF Previewer  that I updated with links to all of these!