TiVo appeared to be on a roll Thursday as, days after winning a significant legal victory against EchoStar Communications, operators of the DISH home satellite system, the company said that it had reached a deal with Cox Communications to install its own software in the digital video recorders that Cox provides subscribers. The deal presumably forestalls any possibility of a similar patent-infringement case being mounted by TiVo against Cox. TiVo reached a similar deal with Comcast, the nation's largest cable company, last year.