Im buying a macbook pro in the next week or so. i have to put vista on it so i can use my work tools, but most of my stuff ( dvds, music, web) will be done using osX. how much hard disk space do i need? i wanted a 160 gb hd, with 60gb for each OS and its respective apps, and the remaining 60 as general storage for both. the problem is that on refurb'ed laptops, the 15" macbook pro's never come with 160gb but only 120gb. would 120 be enough or will i be upgrading in a year or two?