I dont think either, you can put all the data on 1 HD, use a program to make an image, then create your raid array and copy the image on the array, most porgram will let you resize the partition...and RAID souldnt be a problem either!
Asus P4P800DX, P4C 2.6ghz@3.25ghz, 2X512 OCZ PC4000 3-4-4-8, MSI 6800Ultra stock, 2X30gig Raid0