You can get free diagnostic tests from the drives manufacture site. Spinrite http://www.grc.com/spinrite.htm
works the drive to see if it produces any errors. It is hard to tell these days whether a hard drive that makes a sound means imminent failure because i had one that didn't really make any noise and it failed, and then another drive that has been making noises but has been working fine for the past 2-3 years.
My suggestion is to make sure you have a backup of any important data on that drive & if you run an OS on it, if possible make an image of the OS (with a regular backup weekly, monthly or so depending on how often you add new programs, ect. ) so you don't have to go through the process of reinstalling everything.