RAID 1/mirroring is a waste of 1 TB, IMO.....better to get 3 or 4 500-800 GB drives in RAID 5 for less money, which offers increased speed and fault tolerance in the event of a single drive failure...
Instead of 'full backups/mirroring', you can also back up just the data you need backed up fairly easily with Ghost. (can take a 6-7 GB image just after OS and apps install...; back up file folders of photos or important data to just about any smaller drive, or a DVD-RW