im getting 3TB HDD, can someone tell me the different between my book essential and my book live?
i notice that internal and external price is just about the same, so i plan to get the external

please give me an advice,
my mobo has 4 sata port, i currently ald have 4 HDDs, include 1 3TB.
now i plan to add another 3TB for raid 1. i know there is something like PCI-e board which can do RAID(http://intrl.startech.com/Cards-Adapters/HDD-Controllers/SATA-Cards/4-Port-Serial-ATA-RAID-01-PCI-Card~PCISATA4R1), i also read some review which we also can do the RAID just by using windows 7(device manager, right click HDD, Mirror), so which one is reliable?

please consider the RAID feature will still remain after i format my computer/change mobo.

now my 3TB hdd already got files, i worry the files will be gone while im doing the RAID-ing. This would be my first time to RAID, please advice me and warn me which part should I be worry