Dropped, Now won't restart, Can't find hard Disk. Replace Disk?

After dropping this ibook while is was doing a copy, it will startup, but stop when it cannot find the hard disk. The screen lights, but the famous ? shows. I have run the hardware test from the utilities (using the system CD) and the hard disk can't be found. I presume that what I need to do is replace the hard disk drive. Are there other possibilities I should consider?

If replacing the drive is the conclusion, I assume that it needs to be an ATA drive.Thanks in advance for your counsel.