General Electric’s expected sale of NBC to Comcast got one step closer to completion today when the toaster company reached a tentative agreement to fork over $5.8 billion for the 20 percent of NBC that Vivendi owns. The deal, which should be finalized this week, values NBC at $29 billion, or about a billion dollars less than what Comcast agreed to pay for it last week. Expect a joke about this on Thursday’s 30 Rock. [DealBook/NYT]