I have only been following this coin for a few days, so best to do your own research, but my understanding is there is no set minimum. Of course now that I am saying that I imagine someone would be taking this to the "nth" degree, so for you Captain Obvious types out there: if you only have a few Satoshi, the transaction rate would prevent you from receiving anything since the payout would be less than a byte.

I too am trying to wrap my head around this whole concept. I have a small amount of BTC, but seems that this distribution will reward each full BTC with 65.2mb? Huh? so each BTC I hold in a linked wallet will then earn a distribution of 0.062 GBYTE Coin? Interesting way to distribute. At first made me very suspicious..... (the book "To Serve Man" was a cookbook.... that is all that kept running through my head as I considered it),  but obviously I would not be sharing private key... so what could go wrong?  Of course it also seems unlikely that motives are completely altruistic, but if this system is as groundbreaking as it seems to be, it would secure it's inventor's legacy.