What exactly is the purpose of the PS3 Hard Drive?? The reason I'm asking this is because I am debating on whether to purchase a 20GB PS3 or a 60GB PS3. The 20GB can be found really cheap now with the PS3 price drop and all on eBay. I understand that the 20GB and 60GB models differ in that the 60GB models have the chrome trim, built-in wifi, card readers, and of course, larger hard drive. But in reality, these differences don't mean much to me, especially if the price is really different between the two. Furthermore, it is to my understanding that the PS3 Hard Drive can be replaced with any 2.5'' Hard Drive of your choice, so I can essentially upgrade the 20GB PS3 to any size hard drive I want. In conclusion, what are the exact functions of the PS3 hard drive?? To store game saves, videos, music, pictures, what else??