Went to Best Buy yesterday and bought a replacement for my failed drive. Also bought a replacement for another drive that's at least six years old and, I figure, due for a meltdown of its own.
On the advice of a coworker I removed the old drive and gave it a little rap with the heel of my hand. Imagine my surprise and delight when I reinstalled the thing and it fired right up.
I was able to transfer all of my files from the old drive before it failed again, this time probably for good.
Once I had both new drives in place, and all of my files transferred from the old drives, I ran a complete backup of everything on my system.
I don't want to have to go through that kind of worry again anytime soon.
In fact, if I wasn't so senile that I left my wallet at home today, I think I'd go ahead and buy a replacement for my third disk as well.