Ok so I got this Macbook Pro off of craigslist.... yeah yeah dont lecture me of buying it like that but anyways.... I didnt get a cd or any softwear for it I got everything else for it. I used my friends softwear to run Disk Utilities and format the HD so i can do a fresh install of the OS. Well when I try to install the softwear a pop up would come up and say"you are not able to install this softwear on this system" or osmething like that. So now im left with this MacBook that wil not boot up or take the OS. Do I have to go to the macstore and buy the OS and try that? Help?????