Competition is intense among the latest video game machines, pitting Sony against Nintendo Co.'s popular Wii and Microsoft Corp.'s XBox 360.

But the rivalry between the two of the latest video formats — Blu-ray and HD DVD — appears to be tipping toward the former after Warner Bros. Entertainment, formerly a supporter of the Toshiba-backed HD DVD format, defected to the Blu-ray side over the weekend.

Both formats deliver better image quality than conventional DVD players, but only one is expected to emerge as the winner, much like VHS trumped Sony's Betamax in the video format battle of the 1980s.

Attracting movie studios is critical for making the format widespread. Now, just two major U.S. studios support HD DVD — Viacom's Paramount Pictures, which also owns DreamWorks SKG, and Universal Pictures, a unit of General Electric.

Sony Corp. can hope to gain more sales in its core electronics products, including Blu-ray recorders and high-definition flat-panel TVs, if consumers choose Blu-ray. That may also aid it in its struggle against the popularity of the Wii machine from Nintendo, which went on sale about the same time as the PS3, attracting newcomers to gaming with easy-to-play games that use a wandlike remote-controller.

"The PlayStation brand ended the year in a very strong position and clearly indicates more positive momentum going into 2008," said Jack Tretton, president and chief executive of Sony Computer Entertainment America.

"The strong PS3 sales also further establish Blu-ray's dominant position as the high-definition medium of choice for games and movies," he said in a statement.

Sony Computer Entertainment, the Japanese electronics and entertainment company's game unit, said Monday that sales of the PlayStation Portable handheld reached 1.4 million in North America during the Nov. 23 to Dec. 31 holiday shopping period.

Including sales of 1.3 million for PlayStation 2, PS3's predecessor, retail sales of the three PlayStation machines combined reached more than 3.9 million in North America, Tokyo-based Sony said.

Nintendo spokesman Yasuhiro Minagawa said sales numbers for the Wii — a hot Christmas gift this year — weren't available for the same period in the U.S.

Nintendo said previously it had shipped 13.2 million units worldwide of the Wii by October. The Kyoto-based maker of Pokemon and Super Mario games is expecting to sell a cumulative 23 million Wiis by March 31, the end of its fiscal year.

Sony has said previously that it sold 5.6 million PS3s worldwide as of the end of September. The latest will add to the tally but the company did not yet have the numbers from the other regions.

The PS3 has lagged behind the Xbox 360 console from Microsoft, which has sold 17.7 million Xbox 360 consoles globally over the last two years.

In a tie-up that could help sales, Sony said Monday that PlayStation Portable users worldwide will be able to make calls through the popular Internet-based phone service, eBay Inc.'s Skype, starting later this month.