just added a 320 gb hard drive to my original macbook pro. this is the second upgrade i've made to it.  the first when windows vista rtm'ed, was to upgrade the memory from 512 mb to 1 gb.  the only reason for the upgrade was that the ati card can "borrow" memory to provide better graphics performance and vista saw that as less than 512 and wouldn't allow aero.  i've suffered with an 80 gb hard drive (which is the size of my largest zune portable) but now have plenty of space to play with office 2008 and windows 7!