I'm running Windows 7 64-bit and I have a WD 1TB SATA hard drive. My mainboard is an ASUS P6T and I know that it has built in RAID support that I currently have disabled. Although I regularly back up my hard drive with Acronis True Image, I've still become a bit concerned about the state of my hard drive. My question is this..... Although my system currently is a couple of years old and is not RAID configured, is it possible to add an additional hard drive and change it to raid? If yes, are there any rules that I would have to follow regarding manufacturer's, make, model, size, speed, etc. At this point, I'm a real RAID newbie so I don't have a clue where to begin. Can I please get some advice and direction from an expert?
You can still convert your system to RAID, but it'll be harder. The only easy option would be to backup your files and settings, wipe the one hard drive, create the RAID array, reinstall the OS from scratch, and then restore your files and setting. That however would be a pain to do.
The better option would be to create a image of the current hard drive, then save that on another hard drive, create the RAID array, then take the old hard drive image use it to image the RAID array.
The question there would be how to take the backup image and image the new RAID array with it.
Now, as to the choice of hard drive, you'll want to get a second drive that is a close to, if not identical to, the other drive that you want to set up the RAID array with.
VERY important question: why do you think RAID will help alleviate your fears?
There are several types of RAID arrays, all of which do very different things. The two most common are RAID0 and RAID1, each of which typically use two HDD's in one array. RAID0 splits the data evenly between the two and may offer a small speed advantage over a single drive. BUT because the data is split like that, BOTH drives MUST operate perfectly. If ONE of them fails, you lose ALL of the data on the array. Since you seem worried that your existing HDD is becoming unreliable, RAID0 is the worst thing you could do!
RAID1 is the mirroring system - it automatically keeps identical copies of everything on two separate drives. It MAY offer minor speed advantages, but most people think that is too small to bother about. Many treat RAID1 as an automatic secure backup, which it is NOT! Sure, if one drive gets an error the other drive can be used to get the data, and then you can repair the problem and get back to work IF you pay attention to the system messages and use the repair tools. BUT anything that writes bad data to the array will write it to BOTH - a software glitch, malware, a deletion by mistake, whatever. So RAID1 cannot protect you from that type of data corruption - only a good backup plan can do that. If your worry really is the reliability of your existing drive, you might want to consider NOW a reliable backup system, rather that RAID1 which is NOT that.