MB - If you have no intentions of running dual GPUs, you are fine with the Biostar. If this is something you are considering for a future upgrade, look at motherboards with 8x/8x PCIe slots (ASUS P8P67 PRO). The Biostar at 16x/4x has the second slot running at 4x which is less than ideal for the second graphics cards.
GPU - I would agree with swapping this to the HD 5850. ...or the HD 6950.
HD - Scratch the WD Blue. Samsung F3 1TB is a better performer.
PSU - If only using one graphics card you can bring this down to a 650w unit. Some would say 650w is still overkill, but I tend to opt up in this space. Stick with Corsair, Antec, XFX, Seasonic...
If I were to upgrade the GPU to a 6950 would I still be able to drop the PSU? And I do plan on using 1 GPU.