RAID is great technology, but what if your array fails? If you're not spending enough money on backup solutions then you might find that the money you would have spent on adequate backups winds up being spent on expensive data recovery procedures.
Head over to Tom's Hardware and read the article, "RAID Recovery: The Data Knight Kroll Ontrack To The Rescue!," where you'll learn what's involved with data recovery in the event of a hardware failure. The article should prompt you to ensure that you have proper backup procedures in place. If it doesn't then I sure don't know what will!