Comcast (CMCSA) is launching a new streaming service this week that will directly compete with Netflix (NFLX), the latest hit to the once-dominant online movie renter as it struggles to rebound from missteps last year and intensifying competition.

The service, called Xfinity Streampix, will give existing Comcast video customers the ability to watch old shows such as “30 Rock” from its own NBCUniversal and “Lost” from Walt Disney’s (DIS) ABC as well as movies such as “Ocean’s 11” from Warner Bros.

Comcast has struck content sharing deals with Walt Disney, Time Warner, Sony Pictures and Cookie Jar Entertainment as part of the deal.

The service will be bundled for free with certain tiers of Comcast video, including Xfinity triple-play and Blast! Packages, and will be available for $4.99 a month for other Comcast video customers.

That’s cheaper than the $7.99 Netflix charges each month for people to stream videos.

Comcast’s service compliments its existing on-demand Xfinity TV offering, which gives Comcast video customers a selection of 75,000 newer shows both in and out of the home, half of which are free.  

Xfinity Streampix will be available on the web and mobile devices, just like Netflix and Xfinity TV.

“With Streampix, the Xfinity TV service is a comprehensive video solution that lets users watch TV episodes of current seasons and complete past seasons of broadcast and cable hits,” Comcast said in a statement.

The move by Comcast comes at a key time in the streaming market, as Netflix’s blunders from last year continue to hurt its bottom line and drive demand for competing services.

Last month, Verizon Communications (VZ) said it would team up with Coinstar’s (CSTR) RedBox to launch a service similar to Netflix, and Amazon (AMZN) has been striking deals for its own web-streaming service, which is attached to Amazon Prime.

Of course, Comcast’s program does offer a slight disadvantage because it will only be available to broader Comcast customers, just as Amazon’s is only available to Prime customers that pay $79 a year for the free-shipping service.

Netflix may be a bit more costly, but it is open to anyone who signs up.

Still, though, Comcast ended 2011 with 22.3 million video subscribers, which is already more than the 21.7 million customers Netflix had at the end of the year.

“Streampix is another step moving TV Everywhere forward by giving customers access to an even greater library of popular choices to watch,” said Marcien Jenckes, senior vice president of Comcast video services.

Follow Jennifer Booton on Twitter at @Jbooton