The 4gb is not going to be enough space for your vita because your applications and free downloads alone will take up more space than you expect and unless you get this to play one in a blue moon for fun you are going to need more memory. 8gb is slightly pointless because it leaves you on the cusp of being able to download more, but you will find yourself needing to delete other things to make space for new things. If you plan on playing the vita, like, taking it seriously as a gaming device or console, you will need at least the 16gb. That will allow you to have about 3-4 games downloaded and some apps and saved data. If you want to put your whole song library and only play downloadable games and not worry about cartridges anymore, you will def want to look into the 32gb or higher memory cards.Also note that you can download a lot of free demo's, AND sometimes it's quite cheaper to download a game and purchase it directly of the playstation network ESPECIALLY if you have a playstation plus membership, in which case seriously consider the 32gb version. I know it's really expensive, but you don't want to have to pay for a downloaded game only to have to delete it later to make space for a new game you want to download. And there are lots of cool games and demos on this thing, I love the vita and in an ideal world I would have a 60gb memory card, but it's not an ideal world LOL so go with the 16gb or 32gb. Happy gaming!