Nicholas started paying attention to the TV, so we would play an occasional Baby Einstein video for him once every few days or so.  He loved them.  He would smile and coo and make noise – he really enjoyed them.  He started babbling right around 3 months.  He started drooling and teething at 3 ½ months – and started laughing at the same time.  Rolled from back to front at 5 months.  He stood up with help at 5 ½ months, although we think he could have done it sooner.