My real life experience doesn't show the Samsung's slower than Seagate, either Barracuda or 7200.7.
And, if anything the Samsung's are quieter than Seagate. I know that's blasphemy to many here, but I know what I don't hear. I just upgraded a Samsung 40GB drive to a Samsung SpinPoint PATA 160GB 8MB cache drive, and I was concerned about the multi-platter drive being noisier than the single platter 40GB, but that hasn't been the case.
When I went from a 40GB Barracuda IV to the Samsung 40GB there was a definite improvement in disc performance, and this 160GB 8MB cache Samsung flies.