I'm full of Bull%^$#. Check the model number of your computer and determine what MK (mark) you have. MK 1, 2, and 3 require DDR RAM. If you have a MK 4 or 5 you have to use DDR2 RAM. They are not interchangeable. Go to http://www.toughwiki.com/index.php?title...-29 for more information