I am returning my 27 inch I-Mac and getting a replacement (gurgling HD). I noticed some other forum members have done the same and some multiple times. I was curious once receiving the new unit how does one go about re-installing easily bookmarks, addresses and downloaded applications. In other words can one use time machine via external harddrive info from the old machine or does one use migration assistant? What is best approach??? I updated from dual core to quad core for the replacement. I felt it was worth the extra dollars to future proof my machine for future applications. I could not justify the added expense for the reported quieter 2 TB HD and decided to take my chances with the I TB again. Thanks for any responses.