Don't take it for granted, salvage your info, and at most use that drive as a low-priority file backup drive or something. I've had a similar experience, and unhooked the drive, forgot about it for months...found it, hooked it up cause I needed more space only to have it fail in a couple weeks. The first day or two it sounded fine, then it started sounding like grinding gears...I was ignorant of it, just figuring the drive was old. That bit me in the ass, I lost 60GB of backup information and music.
Take my experience and everyone else's advice, salvage the information, ditch the drive before it stops functioning.