Y'all might want to try a program called Crystal Disk Info, which I use. It scans the SMART data from your drives and monitors error and temperature readings. (I have three little icons in my task tray showing the current temps of the three drives I am currently using)

http://crystalmark.info/software/CrystalDiskInfo/index-e.html

Further, check the manufacturer of your drives and see if they have diagnostic software. I use Western Digital exclusively at the moment and they have something called Data Lifeguard Tools, which can scan the drives for errors. (best done before putting data on them as if there are errors scanning might possibly damage the data)

I've been fortunate in that I've never had a drive failure cause loss of data. Always manage to catch it before it got that bad.

Also, I have another program monitoring my CPU and motherboard temps, power supply voltages, and fan speeds. Then there's also one for just my video card, monitoring it's temperature and adjusting it's cooling fan speed as necessary.

Gotta keep these beasts happy.

Brian