Wanting to install a 500 gig esata. I have one of those USB to esata gismos. Should I remove the 160 gig drive install the 500 gig drive and transfer "out to in"? Or leave the 160 gig in place image to the 500 gig and then install it after imaging? I have loads of connectible storage and backups now. Including a fresh time machine backup. Any pitfalls?