I ran into a problem with our Sharepoint 2010 site not allowing pdf files directly it would only prompt you to save it. I found the fix was pretty simple and that was to do the following. Just be aware you are opening up the security on the sites with the files.
1.Verified Adobe Reader option “Display PDF in browser” was selected (it was by default) by opening Adobe Reader and going to Edit -> Options -> Internet -> Web Browser Options
2.Set SharePoint Web Application Browser File Handling to Permissive by opening Central Administration and going to -> Manage Web Applications –> select my web application –> General Settings –> Scroll down and set “Browser File Handling” to “Permissive”.
Till later just Roger