Alright then, this shouldsolve your problem. First install Ghostscript ( I assume you've done this but just in case heres a link to the windows installer of the latest version
Link )
make sure you note down what directory you installed it to, i believe default is C:\gs
Once installed go to control panel -> system -> advanced tab -> click environment variables button. In the new dialog that opens find the path section in the bottom list. Select that and hit the edit button.
In a text box there should be an nice long string of directories. Add to the end of that ";C:\gs\gs8.14\bin" without the quotes (be sure you add the semi-colon before it to seperate the different entries) . Or if you installed it to a different directory replace it with that directory followed by the sub directories \gs8.14\bin
Hit ok a few times to close the dialogs, restart the gimp and opening pdf's should no longer be a problem. Enjoy the GIMP, i've been a GIMP user since before version 1.0, so if you have any other questions feel free to ask
