Win7 (at least I believe it's Win7 and not my M/B drivers/software) is good for letting you know if the drive has a problem. I started getting a message in Win7 that a 1TB had a problem and could fail at any time, so I replaced it. But a few weeks ago, I had a HDD drive fail without warning! I think the heads got jammed at one end of the drive and couldn't move. I got a CLICK, CLICK, CLICK sound every time I powered up my computer. I lost a lot of data with that drive, but my most important stuff, my FSX Payware and other paid for software, were all backed up on another drive that is working fine.

So if you feel you want/need to replace it, then buy a new one. Seeing as you are worried about it, a new HDD will fix your worries, and if it was to fail in the not too distant future, you will regret not replacing it. If I am ever worried about a HDD, I simply replace it. ;)