Interface
The PlayStation 3 uses a hard drive that conforms to the SATA 5400 specification. If you wish to install an IDE hard drive into the machine, you will need to use an IDE to SATA converter device, which includes jumpers and a connector. Read all included documentation before attempting to use the device.
Speed
PlayStation 3 is configured to use hard drives that operate at 5400 RPM (hence the SATA 5400 spec). You can attempt to use a 7200 RPM or even a 10,000 RPM drive, and some might actually work, but if you absolutely must use an IDE drive, select one that runs at 5400 RPM.
Form-Factor
The internal hard drive in a PlayStation 3 is a 2.5-inch form-factor. The case is designed to accommodate this drive size, and drives of any other size (IDE, SATA or otherwise) should never be installed into the 2.5-inch drive bay within PlayStation 3.