If you have Adobe Reader installed but are still not seeing the pdf files, try the following:

In your Internet Explorer
Click on the Tools option (Main menu bar)
Click on Internet Options
Once window has opened click on the Programs tab
Click on Manage Ad Ons
You will get a list of ad ons
Click Name on the headings (This will sort the list)
Look for Adobe (in the name field) and Toolbar (in the type field)
Click on Adobe to select
and by the settings section (near bottom of window underneath the list) click in the dot next to Enable
Click OK
Click OK in the next window

Try go into the site again and the files should show.