I estimate General Electric Company (NYSE: GE)'s NBC Universal is worth between $36.5 billion and $42.5 billion -- that's down 13.7% at the low end -- from the $42.3 billion to $52.7 billion valuation range I calculated last July.

NBC Universal did poorly in 2007. Revenues declined 5%, or $0.8 billion, in 2007, primarily from the lack of current-year counterparts to the 2006 Olympic Games broadcasts ($0.7 billion) and 2006 sale of television stations ($0.2 billion), lower revenues in its broadcast network and television stations as a result of lower advertising sales ($0.5 billion) and lower motion picture revenues ($0.1 billion), partially offset by higher revenues for cable ($0.4 billion) and television production and distribution ($0.3 billion).

Segment profit improved though -- it rose 6%, or $0.2 billion, in 2007 as improvements in cable ($0.2 billion), television production and distribution ($0.2 billion), motion pictures ($0.1 billion) and the absence of Olympic broadcasts in 2007 ($0.1 billion) were partially offset by the lack of a current-year counterpart to the 2006 sale of four television stations ($0.2 billion) and lower earnings from its broadcast network and television stations ($0.2 billion).

To calculate NBC Universal's value I compared it to other publicly traded TV networks like Viacom Inc. (NYSE: VIA), The Walt Disney Co. (NYSE: DIS), or CBS Corp. (NYSE: CBS). Those three trade at Price/Sales (P/E) ratios of 20.2, 16.1 and 18.6 which gave me a range of values between $36.5 billion and $42.5 billion when I multiplied those P/E ratios by NBC Universal's 2007 estimated net profit of $2.57 billion.