uhm ok let me explain interfaces for a bit
Sata, and Pata(IDE) are both Internal interfaces, they are not setup to go outside a case or enclosure of some type. Pata is the old tried and true 40 pin ribbon cable thats been around a very long time, Sata is a relativly a new tech, uses a 7 pin cable, and new power connector. Internal hard drives, and optical drives(cdroms) usually connect to one of these interfaces.
USB and Firewire are external interfaces, they are designed to be external.
An enclosure does 3 things, 1. it houses an Internal drive, 2. It converts the signal from an Internal interface(PATA/IDE) to an external interface(USB), 3. provides power.
Basic example of how the interfaces would be
Your not going to see any differences between SATA and PATA interfaces because your bottleneck will be in the USB or firewire interface. You can save about 10 dollors by getting a PATA drive. The bad is that support for PATA is probably gonna go away in about 3 years.