I have a 5-year old hard drive (bought new at the time), but it was sitting in my closet for 5 years, unused. I have just started using it, and seems to be getting a whirring sound (rather distinct from the other noises like fans etc.). I ran a few diagnostics tests, like Seagate's SeaTools, and the SMART test, and a few generic tests and all passed. Should I be concerned? Is there any other test that I should run?

It's an internal IDE WD 5400RPM drive. Being used for a desktop, which is itself pretty high-end (AMD Phenom II X6 1100T, AMD Radeon GPU etc.), but would be used rather occasionally to begin with (avg. 1-2 hrs. per day).

Thanks for any pointers.