It will work but you can save some money by getting a Samsung Spinpoint f3 which will be just as fast as the WD.
Also for mainly gaming you don't need 8GB of RAM, so if you are looking to shave off some pounds, you can do there.
I'd also opt for the MSI P67A-GD53 over the G45 just because the GD53 has full Military Grade components and it's generally a better board as the GD53 is a downgraded GD65 where as the G45 is an upgraded C45 if you see what I mean.