Hi,
MS Windows Journal is a program used on XP Tablet PC Edition.
If the file you are trying to open was created in this program and you are trying to open it through regular XP-pro or XP-home you will need the following download:
http://www.microsoft.com/downloads/details.aspx?FamilyID=fad44098-8b73-4e06-96d4-d1eb70eacb44&displaylang=en
If the file you are trying to open was not created in MS Windows Journal, try right-clicking the pdf file (or any pdf file on that PC), selecting Properties and changing the "Opens with" configuration to tell windows to use Adobe acrobat or other pdf viewer installed on the PC for opening pdf files.