This is how I was successful in getting the .fdf file to finally open. Adobe would open, but wouldn't display anything.
First go to http://foxitsoftware.com/downloads/ and download Foxit Reader.
Once you install it, Click File -> Open. You may have to change the type box to fdf at the bottom.
It will then ask you if you trust this site. If you do, click yes and it opened the site for me. I logged in and repeated the previous steps.
At this point Firefox opened the fdf in adobe with boxes that I could type in. From this point you can type in what you need and print it.
If you wanted to print it off as a pdf and save the stuff you typed in the forms, you will need a pdf printer.
I recommend http://www.cutepdf.com/Products/CutePDF/writer.asp. Install it and the do file print and select cutepdf printer.