TiVo on Wednesday said it extended its TiVoToGo portable video service to pocket computers and mobile phones running Microsoft software, as the television recording company beefed up its offerings in an effort to differentiate from its rivals.

TiVo said TiVoToGo is now available on Microsoft Corp.'s Windows Mobile-based Portable Media Centers -- paperback-sized devices that can play digital music and videos -- as well as certain Windows Mobile-based Smartphones and PocketPCs handheld computers.

The move improves on TiVo's TiVoToGo initiative, announced earlier this year, that allows users to shift recorded TV programs to a personal computer in the same home.

The new feature lets them travel with those shows, and watch them on devices made by companies such as iRiver, Samsung Electronics, Hewlett-Packard Co., and Dell Inc.

TiVo signed a key digital video recorder (DVR) distribution deal with cable provider Comcast earlier this year, quelling investors fears about its plans to grow subscribers to its fee-based service. But it still faces competition from cable and satellite TV providers, as well as consumer electronics makers.

TiVo executive Matt Wisk said services like its powerful on-screen program guide and TiVoToGo, which is free to monthly-fee-paying subscribers, offers consumers a premium service to generic DVRs that only record and play back shows.

Microsoft said this feature could spark demand in the portable digital video market, whose growth has been slack compared with the explosive expansion of the portable audio market, which is fueled by Apple Computer Inc.'s iPod. Video phones could also benefit.