I can never remember what RAID numbers mean what so in the interest of clearing yet another sticky note from my desk, here's a simple reminder post.
RAID 0 - Striped (fast)
RAID 1 - Mirrored (redudant)
RAID 5 - Striped with parity
RAID 0+1 - Striped and mirrored
RAID 1+0 - Mirrored and striped
Wikipedia has a really good, in-depth article for more info.