In the case of most old television sets, the environmentally sound thing to do is to keep the old set and hook it up to a Digital TV Converter Box.

If you feel you must replace it with a new TV, select an energy efficient TV.

Most old CRT sets use less energy than LCD or Plasma TV’s. LCD TV’s are more energy efficient than Plasma TV’s.  A smaller screen TV is more energy efficient than a larger screen TV.

See this link for more information about choosing an energy efficient TV.
http://www.sciam.com/article.cfm?id=choosing-an-energy-efficicient-tv

See this link for information about EnergyStar qualified televisions.
http://www.energystar.gov/index.cfm?fuseaction=find_a_product.showProductGroup&pgw_code=TV

Dispose of that old TV properly. Recycle electronics for free at the Illinois EPA’s and the City of Chicago’s site at the Goose Island Facility in Chicago.

Consult the Solid Waste Agency of Northern Cook County (SWANCC) on how to recycle your old TV and other electronics. http://www.swancc.org/recycling/computerelectronicspermanentdropoff.html