|Find a pdf file in "My documents"or whereever on your hard drive. Right click on the document and in the window that pops up click "open with". In the next window that opens, if Adobe is listed then choose that if not then click "browse" and find the exe file for adobe and choose that.|
In Windows help it says:
Open the folder that contains the file you want to change.
Right-click the file you want to change and then, depending on the type of file, either click Open with or point to Open with and then click Choose default program.
Click the program you want to use to open the file.
Do one of the following:
If you want all files of that type to open in the same software program, select the Always use the selected program to open this kind of file check box, and then click OK.
If you want only that file to open in the software program this one time, clear the Always use the selected program to open this kind of file check box, and then click OK."