Typically, I'd say, run RAID-1. When it's time to upgrade, get two more identical drives, plug-em in and set up another mirror. Then, for Windows, delete your system hdd from the device manager and reboot to a Norton Ghost CD (assuming it supports your raid controller). Clone the partitions to new mirror. Power off, remove old mirror, boot to a new mirror. It will most likely re-detect the new mirror and request a re-boot, after that you're good to go on. Old drives can be wiped and sold on e-bay. Or turned into a backup volume.
