Hi. I'm hoping to upgrade the HD on my old MBP (15" from 2006, model A1211). The only two options available to me are Seagate Momentus G 7200.4 (only G, no non-G) and WD Scorpio Blue (which spins at 5400 rpm). Both 500gb. I'm posting to ask whether I should expect problems with either one. I know there has been a lot of discussion about the Seagate Momentus G 7200.4 about stuff like beeping noises and incompatibility with the MBP's sudden motion sensor. I've searched and read lots of posts but was still left with an unclear picture. First, there was talk about beeps and clicks with various 7200-RPM HDs. But it seemed the discussion was limited to unibody MBPs. I found a few, but perhaps unreliable, accounts of people enjoying their 7200.4 in their 2006 MBPs. Can anyone give me a clear answer as to whether this problem plagues unibody MBPs only? Second, there was talk about "incompatibility" between the G-force system in the Seagate and the MBP's SMS. All I could find was mentions that maybe there was an incompatibility and suggestions to disable the SMS. I couldn't find clear accounts of what exactly this incompatibility is, in fact. I was also unable to clearly understand the ramifications of the "incompatibility" and to what extent these were corrected by disabling the SMS. I would greatly appreciate it if someone familiar with these issues can give me a clear picture of what issues I might face with either drive. Thanks.