it all equals out to negligble heat and power consumption. A faster drive will make boot times shorter, and decrease the lag between starting up programs as well as loading game levels. It wont give you faster fps.
there is minimal differance between the 2 speeds on a drive of this volume. granted the 7200 will be slighly quicker at loading game levels and large files (like movies...if you were to do editing), it will slightly cripple your battery life (~5 minutes/charge)