I've been doing some research on the differences between desktop and portable external hard drives. I was amazed at how little discussion there is concerning the speed differences. I have some preconceived ideas that I'm not sure are correct. Can someone in the know help out? Thanks! 1) 7200rpm drives are noticeably faster than 5400rpm drives. 2) Most desktop external hard drives are 7200rpm 3) Most portable external hard drives are 5400rpm 4) Desktop external hard drives will generally be noticeably faster than portable ones. Not sure if my logic is correct??