4GB or 8GBmicrosd card

The local store I can pick up a Raspberry Pi 2 from and all required acceserios have run out of 8GB class 10 cards (Kingston). Will a 4GB be enough???

Only intending to use this for a Media Centre and streaming

Thanks
Ben

Although you can install on 4GB in my opinion you are likely to run out of space once you start making good use of the system, so I would try to get an 8GB card if you can.