To configure Acrobat as a helper, follow the steps below:
Acrobat 6.0 on Windows:
Select 'Preferences' from the Edit menu.
From the Preferences dialog box, select 'Internet' from list on the left.
Uncheck 'Display PDF in Browser' under Web Browser Options.
Acrobat 5.0 on Windows:
Select 'Preferences/General' from the Edit menu.
From the Preferences dialog box, select 'Options' from list on the left.
Uncheck 'Display PDF in Browser' under Web Browser Options.
Acrobat 4.0 on Windows:
Select 'Preferences/General' from the File menu.
From the General Preferences dialog box, select 'Options' from list on the left.
Uncheck 'Web Browser Integration' under Options.
After the preferences have been set, you can click the PDF link again. You will
then be prompted to save the file to your machine. After you save it to your
machine, a prompt will then ask you if you want to open the file.
source: http://www.instron.us/wa/home/PDFConfig.aspx