If you know for a fact that you're not going to be using 1 TB of space, just get one hard drive. Plus, get a cheaper motherboard, then use the money you saved towards a better GPU.
I have a 1.5 TB hard drive, I haven't even used 200 GB yet, plus the motherboard is only good for overclocking, like what Righteous said. With stock cooling, you won't be doing any overclocking anyway.