Try downloading the update again and note where it downloads or change the download location to your desktop. If the program does not run, then open the folder it downloaded to (or on your desktop_ and click the icon to run the program.
BTW, do you mean Reader 7? Acrobat is the program that you have to buy that allows you to make PDF's. Reader is the free program that allows you to view/print PDF's.
Another option would be to download PDF Creator which is a free program that allows you to make PDF's.
http://sourceforge.net/projects/pdfcreator/
Using PDF Creator may allow you to change the size of the PDF.