Hi everyone, Forgive me as I am new to the mac world! I have a Macbook Pro which I bought as a refurb. I've ordered some memory to upgrade it to 8GB, and a hard drive to upgrade it to 500GB. The booklet that came in the box tells how to physically replace the drive, and I've done a full backup with Time Machine to an external hard drive. But I'm confused about how the OS will get installed on the new (blank) drive since the MBP didn't come with a disk. Does it retrieve it all from the internet? How does this work?