I also have adobe reader latest version 8.1.2 and adobe acrobat 7.0 professional full program .
I can tell windows to associate either reader or full prg to open pdfs and usually works ok.
I also am creating an information and training cd with autorun pro enterprise software.
If I associate a pdf with acrobat full version it starts acrobat and displays the pdf, but when I associate it with reader it displays a windows error message saying that there is no association with the file type you have selected or words to that affect.
This is annoying as obviously most people will not have the full version only the reader.