ESPN: The 24-hour sports channel--known best for its "SportsCenter" updates, plus live NBA basketball, college basketball, tennis, golf, NASL soccer, college, Canadian and (next year) USFL football, among a hundred other events--can be found in Arlington, Gaithersburg, Alexandria and certain parts of Prince George's County. It will almost certainly be part of systems in the District of Columbia, Fairfax County, Montgomery County and the rest of Prince George's County. It's a basic cable service, meaning there's no extra charge for ESPN above the basic cable fee.
USA Cable Network: Sports-heavy entertainment channel, home of Thursday night major league baseball, Thursday night NBA, Monday night NHL, Wednesday night NASL, plus college football and basketball, pro tennis, boxing, golf, racing and wrestling. A basic cable service.
Superstations: Arlington has Atlanta's WTBS-TV-17, Braves/Falcons central, but has dropped New York's Mets/Rangers station, WOR-TV-9, because of a satellite switch. Prince George's system will be area's most extensive, carrying not only Atlanta and New York (the Yankees' WPIX-TV-11 is also a superstation) but also WGN-TV-9's Cubs and Bulls from Chicago. Expect Fairfax, Montgomery County and District to carry at least two superstations, probably more. Superstations are considered basic cable.
HBO: Known best for movies, also features a fair amount of boxing, and special events such as live early round Wimbledon. This is pay cable--it costs more than basic cable. Available on most area systems, plus the area-wide microwave system known as Marquee Television.
Marquee Television: Pay television, or subscription television (you pay a monthly fee for the decoder that turns their microwaves into television signals). Currently features only HBO, but is waiting for approval to add at least one new channel.
Super TV: Orioles home games, boxing interspersed with movies on this fast-growing Washington/Baltimore pay-subscription system, which costs about $20 a month. Expect any new Super TV offering to be heavy on local/regional sports like home Orioles and Bullets games, ACC basketball.