buying ps3 super slim got a few questions?

[Krystalle]

ok so should i get the 12gb or 500gb bcos i heard sony were doing this thing on the new super Slim you can change there hard rive or something is that true? bcos if it is im just gonna buy the 12gb and get more hard rive later on bcos the 500gb is ?250 and the 12gb is ?135 depends were you get if from bcos there are sales so which one should i get?
and the games i play are call of duty and far cry 3 and game's like that