On Feb. 17, 2009, television broadcasters will transmit only digital TV signals and not analog signals.  Televisions (no matter what type) connected to cable, satellite, or one of the new telephone company fiber-optic services should continue to work as they do now.  Televisions connected to an antenna might or might not work after Feb. 17, 2009. That depends on the type of TV.

How to Survive the Digital TV Transition
Article from Consumer Reports describing which televisions will work and which won't, and what to do to get your television to work.

National Telecommunications & Information Administration
Digital Television Transition and Public Saftey Act of 2005

Digital Television (DTV) Tomorrow's TV Today (FCC)
Digital Television basics, information & application for converter box coupon and how to purchase a DTV.

DTVTransition.org
"Are you Ready for the DVD Transition?", an online quiz, benefits of DTV and links to other resources.