You're saying 8GH/s is worthless?
8Gh/s is worthless even if you get it for free!
You have no idea how high diff is!
30gh/s and even 50gh/s is worthless right now.
I have 170gh/s and I am earning 0.07btc/day. And in abouth a month I am pulling a plug for them!
What do you think you will earn with 8Gh/s???
Just forget about it.
Also there is no sha-256 coin more valued to mine instad of btc. At least not that much to make any diference.