Yes, the digital adapter is $1.99 a month. I accidentally made the mistake of thinking that you could get all the channels covered in the Digital Preferred service similar to Verizon FiOS TV's digital adapters (which was my previous TV service) but the customer service representative at Comcast told me that I could only get between channels 2 through 101. When I found that out, I quickly changed my subscription from 2 digital adapters to 2 SD converters. Sure the SD converters cost more each month but I got more channels plus On Demand.
In my area the Comcast channels above 100 are available but not all channels that are available on a cable box are available on a DTA. Soon however an HD-DTA will be available which will have all channels available on a cable box except for premium channels such as HBO and VOD.
Nice Atari icon there. Too bad that Atari had recently filed for Chapter 11 bankruptcy here in America. The 2600 and 7800 systems were my first video game systems I had ever owned during the 1980s. Anyway, I live in New Jersey and the Comcast representative on the phone told me that the only channels I could get with the digital adapter are local channels (including local access channels), The Comcast Network (which is on channel 8 in my area of NJ) a few selected basic cable channels and Weatherscan (which is channel 101 in my area) and that is all. I was also told that I couldn't get On Demand using a digital adapter which was the same case when I was a Verizon FiOS TV customer but at least I was able to access all basic and premium channels with their digital adapter. Perhaps after my 2 year contract with Comcast expires, I might return to FiOS TV if I am not totally satisfied with Comcast's service during the next 2 years.