Adobe Reader
Adobe Reader is the free version of Adobe Acrobat Professional. It is used to view and print PDF files.
 
Due to its popularity, it is frequently targeted for security holes and malware attacks, so if you are prompted to update this software, please do.  Make sure the update is only for Adobe Reader.  If you see any updates for Adobe Acrobat Professional, or Adobe Creative Suite, DO NOT run those updates as they will break the KeyAccess link and you will not be able to run those programs until they can be re-patched. 
 
To download the most recent version of Adobe Reader, please visit this website. http://get.adobe.com/reader Be sure to UNCHECK the option for McAfee Security Center.
 
Alternative for Adobe Reader - Sumatra PDF
If you are having problems with Adobe Reader and need to open a file immediately or unsatisfied with the program's performance try downloading SumatraPDF for Windows.
 
SumatraPDF, also known as Sumatra, is a free and open source PDF reader. The program also opens Open XML Paper Specification, DjVu,EPUB, XPS, CHM, CBZ and CBR, and MOBI files.