@Rolex, the first thing you need to know is RAID is NOT backup. Setting your computer up in a RAID wouldn't have stopped a loose connection either... in fact if anything it would have cost you more money because you would have thought the drive was bad then replaced a perfectly good working drive with a new one.
RAID has is purposes, but acting as a backup is not one of them. RAID is for greater up times or higher performance or in some cases a mixture of both, but again - backups it is not. We use RAID 1 on the RCNT server, it's purpose is for redundancy - if one of our SSD drives crap out we can still stay online until that drive is replaced. I run RAID 10 on my home NAS for higher performance out of my spinning disks while also providing protection in case a drive bites the dust. You also probably do NOT need a RAID controller card as many newer motherboards already support RAID natively so check your motherboard manual before buying anything.
If data protection is your concern then what you need is a good backup solution - not RAID (have I said that before?). My recommendation, and what I use myself, would be to use
CrashPlan.
For $60 a year or $5.99 a month you can get a
CrashPlan unlimited storage plan on one computer. The interface is extremely easy to use, you can simply pick the folders that you want to protect or tell it to protect the entire computer. It does it's work in the background so it's a set it and forget it type operation really. They also don't charge you to restore files, like Amazon Glacier does and restore is also very easy. Speaking of restore and backups, Crashplan will keep "versions" of your files too (you decide how many) which is perfect for that nasty trojan that goes around and encrypts all your data then demands a few hundred or thousand to get your files back. Simply clean computer, restore previous version before encryption and you're good to go.
There are other backup services out there, but CrashPlan is what I use and would certainly recommend. This sounds much more like what you need, a full, nearly real-time backup of your important files, which RAID will not and cannot give you nor is it designed to.