Creating a RAID1 array and preserve old data

I'm about to build a new machine based on the Asus P8Z77-V Deluxe motherboard and windows 8 pro x64. Windows will be clean installed in UEFI mode on a SSD while data will reside in a RAID1 array. For the array I'm planning to use two HDDs from a RAID1 array in my old system, the motherboard of which is an Asus P5W DH Deluxe. I would very much like to keep the data in the old array. So, is...