Comcast added nearly 1 million revenue generating units (RGUs) in Q1 -- its highest growth rate yet -- driving revenue in its Cable business to $5.6 billion. Some highlights for the quarter:Video revenue increased 6% to $3.6 billion in Q1, reflecting a 1.3 million or 14% increase in the number of digital customers from the first quarter of 2005. Comcast Cable ended the quarter with 10.1 million digital cable subscribers, a 47% penetration rate of the Company's 21.5 million basic cable subscribers.Growth in video revenue and digital cable subscribers...