Do either of your hard drives show up in BIOS ? that would be my first port of call. If they do then they are working, but could still be dying. Have you tried swapping their boot order (slave or master - IDE)
Not necessarily. The BIOS just checks the drive interface. That could be good and the BIOS would correctly detect the drives.
But if the drive internals were bad, the first sign of failure would occur when you tried to read/write to them.