The best way, IMO, is to use an add in RAID card. Why -- because you aren't dependent on a motherboard RAID controller. You can move that RAID card to any motherboard you desire and move your data with it.
For maximum versatility, I recommend a network attached appliance -- NAS unit. That way any device on your network has easy access to that storage space. Look at Thecus, Synology, Q-NAP.
BUT, what you need to do is setup a RAID 10 -- striped and mirrored. You can create a striped volume in Windows, but I don't know if you can do a striped and mirrored without RAID hardware.