How long to earn fractions of bitcoin
It depends by the machine, of course, but keep in mind that difficulty changes as time goes on. You should look at that specific index in order to aknowledge it correctly. By now, it takes about 1 year to get 1 BTC with your hardware, supposing no difficulty increases. I do advise you to mine other currencies (BTB or others) and then convert them into BTC... that's easier this way!