A question about RAID1

[Captain B.O]

Hi there, I'm wanting to upgrade my computer from it's ancient 150GB (!!) IDE drive to a nice large SATA drive. I was thinking of making a RAID1 array for storage but have one question about it. I always assumed that if one drive dies the other drive can be used outside the array, but somewhere I read if the controller breaks you've basically got two unreadable drives. Can someone clarify this for me? Are the drives in a RAID1 array usable as normal drives or can only the RAID controller (perhaps even the specific model) read the drives?

Thanks.