Caviar series drives are in the 3.5" desktop form factor, while the Scorpio series drives are in the 2.5" laptop form factor.
SATA II vs. III for hard drives is basically irrelevant because no hard drive has transfer rates that get anywhere near the bandwidth of SATA II, let alone SATA III. It's only for ultrafast devices such as the fastest SSDs where SATA II actually becomes a bottleneck and you need SATA III to get full performance.
You can download a paper from this Microsoft web page
that tells you how to configure your SATA ports as removable or non-removable by configuring the Registry.