I own a MacBook Pro (Intel Core 2 Duo) with Tiger installed (10.4.11). After reading several articles confirming that the Snow Leopard upgrade disc works on Tiger, I decided to purchase the $29 upgrade disc. I pop the disc in, restart the computer, and (after choosing the English language option), am greeted with an error message: "Mac OSX cannot be installed on this computer. This disc requires version 10.5 or later to be installed." Anyone have any insight on this?