Well, the hard drive would store all of the demos, videos, and games you download. If all you're going to do is watch movies or play games from a disk, you don't need to worry. Each game you have will take up space on the hard drive. They can range from about 300 Mb to over 4 Gb. For example, Resistance 2 takes up only about 350 Mb. Metal Gear Solid 4: Guns of the Patriots takes up about 4.6 Gb. Assuming that each game takes up about 4 Gb (which they usually don't, it's more like between 1 or 2 Gb. I think Metal Gear is just an exception) you're good for at least 10 games, probably between 20 to 30. This also means you'd be able to hold less demos and videos over time. However, if you're gonna be a moderate gamer who will be fine with keeping only a few demos at a time, you'll be fine. I personally have the 120 Gb version and am a pack rat when it comes to demos. I have approximately 30 demos and videos and have only about 30 Gb left. However, if you ever run out of memory, I believe that you can swap out the PS3 hard drive for an equivalent laptop hard drive. I've only heard about it and don't know the specifics, but you can probably google it if you'll ever need to.