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I just put a WD Scorpio Blue 500 GB (5400 RPM) into my Macbook. Got some great reviews and works like a charm so far. $99 on Newegg....

I recently put the same drive into my MacBook and have experienced no problems. It just works. I did not, however, get this good of a price since I went to Best Buy. I paid $138 something.
 
barefeats.com, baby

they publish speed tests with many different HDs, and most recently, I believe found that the new 500GB Seagate Momentus @7200 RPM was the ultimate internal laptop HD. For externals I've had very good luck with OWM Mercury Elites, but would stay away from their RAID configurations due to the loud fan.
 
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