As Radeon said, you could use a bigger PSU. You don't need it now, but if you upgrade later you will have to replace it. 430W is also cutting it pretty close for a 7870, many of which call for a 450W or so PSU. As time goes on, your PSU will degrade and power will decline. It will take a while, but could eventually damage other components, namely the graphics card.
Also, I would recommend making the leap to a WD Caviar Black. They are a better drive and have a five year warranty.