U.s. spending on video games for personal computers hit $1.4 billion in 2005, according to an estimate released by market research firm NPD Group on Wednesday.

Online subscriptions to PC games and gaming Web sites accounted for about $344 million of those annual sales, said NPD.

Faster Internet connections are making it easier for consumers to play games online and to download game content that had once only been available in stores, said NPD, which last year began tracking online subscriptions.

Subscriptions to play specific online titles — such as "World of Warcraft" from Blizzard Entertainment and Vivendi Games (V) — reached roughly $292 million in 2005, with about 1.4 million paid subscribers.

Casual gaming sites, such as Electronic Arts Inc.'s (ERTS) Pogo.com or RealOne Arcade from RealNetworks Inc. (RNWK), had sales of around $52 million in 2005 and had 1.05 million paid subscribers. Such sites often include puzzle games that can be played in a 15-minute coffee break.

Major U.S. game publishers such as EA and Activision Inc. (ATVI) expect downloads to grow into a substantial business, although that part of the industry is just starting out.

NPD analyst Anita Frazier said digital downloads appeared to have contributed about 3 percent of total PC market sales in 2005, which would amount to about $42 million.