Our survey of the top five cable operators--Cablevision, Charter, Comcast, Cox Communications, and Time Warner Cable--indicates that Cablevision and Comcast customers are the ones who will be most affected by this transition.

Here's the full story.

: Cablevision will be the first major cable provider to offer new customers digital-only service for its expanded basic channels. Broadcast and local channels will continue to be simulcast in analog for the foreseeable future. Many expanded basic channels will continue in analog as well (45 channels currently), but Cablevision has begun eliminating various duplicate analog feeds of stations that it carries in digital format. The affected channels include ABC Family, AMC, BET, CNN Headline News, CSPAN, FUSE, Galavision, History, Lifetime, MSNBC, MTV, MTV2, Spike TV, TV Land, VH1, and WE. To receive these channels, you must attach a cable box to each television you plan on using, at a cost of $6.75 per box per month.

The company says that more than 91 percent of its 3.1 million customers have digital service, but a spokesperson acknowledges that this figure doesn't distinguish between subscribers with all-digital setups and subscribers who have one cable box in the home for digital service but additional TVs set up for analog service. (For example, a subscriber may have a cable box connected to a in the den, but no such arrangement for TVs in the bedroom, kitchen, and basement--and yet with analog service the subscriber can currently receive MSNBC on all four TVs.) Cablevision is offering its analog-only customers the option of accepting a free digital set-top box and free digital navigation for one year. If you have multiple TVs, however, you get no additional break.

: Charter will offer an analog simulcast of broadcast stations. According to the company, some regions have migrated to the digital tier, but as yet it has no plans to go all-digital systemwide. Charter says that it's treating the digital migration as a gradual process. A spokesperson notes that only a handful of channels have gone from analog to digital in expanded basic, but eventually all of them will migrate. "We have tried not to make any sweeping changes for our customers," the spokesperson says.