It's not going to be possible to watch the Opening Ceremony for the 2012 London Olympics if you're trying to see it on TV at its actual starting time. An NBC tape delay will knock the starting time on American television back three and a half hours from its official starting time of 4 p.m. ET -- 9 p.m. local time in England -- to 7:30 p.m. ET.
Though the Opening Ceremony will not be among them, most events in the Olympics will be streamed live on the internet at NBColympics.com, assuming you meet their restriction. According to the site, you can stream most events only 'with a cable, satellite or telco TV subscription that includes MSNBC and CNBC'.