How important is HDD-Speed for the overall system performance? I just got a G5 DP 2.0 and need to replace the 160 HDD with two 400-500 GB HDDs (they will be used for Photoshop work on raw Files and SD-DV Video, maybe HDV in the future). There are a lot of reviews on sites like barefeats.com, but the difference between the speed kings and the slower drives only seem to be a few percent (with all 7200rpm). Will I really notice a big difference between let's say a Western Digital Caviar SE16 or Hitachi Deskstar 7K500 and a Samsung SpinPoint T166 or a Seagate Barracuda 7200.9? (Recommendations for a not to slow, not to expensive, not to loud drive are of course welcome).