In the fourth episode (School Reunion) of the second series, we will get the return of Sarah Jane Smith and K-9!
Sarah Jane was a companion to both the Third Doctor (Jon Pertwee) and the Fourth Doctor (Tom Baker).
She did a very good job at screaming at the sight of an alien menace, which is the primary job of a Doctor Who companion...
After watching both seasons of the New DW series, I'd say the best of the classic beats the best of the new series.
Sure, the new series has strong characterization, witty dialouge, and emotional dramatic scences. My problem with the new series is that the episodes feel "rushed". Russell T Davies is cramming everything into a 45 minute time slot. As a result, there are a lot of plot holes and too quick solutions in the episodes.