Also evaluate whether you can throw money on an exchange and make more money than if you bought the hardware. You can't ignore the fact that this setup you are proposing will give you about about 2 GHash/s (give or take) and cost you about 1.1 to 1.3 kWh of electricity. At $0.15 per kWh, that works out to just over $4 per day to generate bitcoins. Network difficulty and value fluctuate (difficulty going up and value going down). You have to take these factors into consideration if you choose to sink some money into hardware.