just to interject... cache is generally important... sort of acts like a flywheel - allows momentary lapses in the ability for the hard drive to physically keep up with data I/O, but with streaming content, such as audio and video, cache becomes a little bit less important, because ultimately it is the long term sustained rates that are more important. cache generally helps with short term burst speeds.
like mentioned, SATA I vs SATA II should have no real world differences in single drive interfaces. it is not until you start using expanders, chaining multiple drives on a single serial lane does the interface speed come into play.
honestly, I'd look at 3.5" 7200RPM solutions. both that you mention are 2.5" HDD solutions. you would loose the ability to buss power the drive (can be extremely important), but generally, 3.5" desktop based drives are cheaper, ultimately allow for larger capacities, and are higher performance. the down side is that they are physically larger and require external power to operate.