Sony, Nintendo and Microsoft think that connecting their gaming consoles to the Internet should boost future revenues, but the trio have at least one serious obstacle to overcome first — an apparent lack of interest from gamers to pay for such services.

A study released by the Interactive Digital Software Assn. at the E3 vidgaming confab in Los Angeles last week says while 31% of frequent gamers play online (up from 18% in 1999), only 6% are willing to pay to play.

“Online games hold tantalizing promise for growth,” says IDSA topper Doug Lowenstein. “But you’ve heard this before. The same analysts who today talk of online games generating $1.5 billion by 2005 forecast five years ago that online games would generate $1.5 billion by 2002.”

The study already has prompted Sony to make online gameplay free for users of its PlayStation 2 system. Microsoft’s Xbox, however, will charge a monthly fee.

One positive note: Online gaming sites are growing in popularity. Internet research firm Nielsen/NetRatings says such sites attracted more than 28 million Web users in April — 24% of total Internet users.

The top site for the month was Microsoft’s MSN Gaming Zone with 7.2 million surfers — a group the software giant hopes will make the leap to connect their Xboxes to the Web.