I know there's a million of these, but I've never had a Macbook so I'm not sure... how much space do apps take up? I know it depends on how many you have, but if you download a few games, some etextbooks, some other miscellaneous apps, are they more like the size of word documents or mp3s? Assuming I use a program to rip the music from my iPod to my new computer (easier than dealing with my messy and spread out collection on my current computer), I will be filling it with 40.1 gb of my iPod's data. Since I don't really have anything else except for some photos and documents, I'm thinking 128 gb is probably fine, but it just seems like so little. Is the SSD upgradeable if I decide I need 256 gb later on?