Looking for a high capacity back up drive, in the range of 400gb's. I was initially looking at the Western Digital WD3200KS drive but though it might be too small and would go for a 400gb drive. Does their 400gb drive compare to it in terms of performance? It will only be used as a back up drive, holding movies/games. I have a raptor setup for my boot drive and primary games/apps. any suggestions?