If I invest 2000$ dollars how much bitcoin I could mine in 1 year?
Thanks in advice
1) For GPU, mining scrypt is 5-6 times more profitable compare to Bitcoin.
2) If you really want Bitcoin so badly, you can always mine scrypt (i.e. litecoin, feathercoin) and then convert them to bitcoin using Btc-e.
3) If you don't want the hassle, you can point your miner to middlecoin.com. Middlecoin help you to choose the most profitable alt-currency at the point of time and then auto convert all of them to Bitcoin with a small fee (3%).
4) HD 7950 and 7970 are both good for GPU mining, as an alternative, you can wait for the new GPU Radeon R9 290x which is coming out next week.
Hope that helps