That's what I thought
That's what I thought. But I wanted to double-check, just to avoid any restocking fees. So I wrote to HP support email and they said:
I would like to inform you that your notebook internal hard disk drive bay only supports 9.5mm ATA-100 hard disk drives.
Additionally if you are interested in purchasing the hard drive, the drive specifications are 100.0GB ATA-100 EIDE hard drive - 4,200 RPM, 2.5in form factor, 9.5mm height. The cost is $575.00.
I would never even consider buying a drive at DOUBLE RETAIL PRICE under any circumstances. But setting price aside, the answer from HP seems geared towards sales and not about giving accurate information to the customer.
So thanks for your response. I think I'll go grab that drive tomorrow.
Jerry