It was just another Wednesday on the sprawling Internet chat-room network known as IRC.

In a room called Prime-Tyme-Movies, users offered free pirated downloads of The Passion of the Christ and Kill Bill Vol. 2. In the DDO-Matrix channel, illegal copies of Microsoft's Windows software and Prince of Persia: The Sands of Time, an Xbox game, were ripe for downloading.

In other chat rooms, whole albums of free MP3s were hawked with blaring capital letters. And in a far less obtrusive channel, a hacker may well have been checking his progress of sneaking into the computers of unsuspecting Internet users.

Even as much of the Internet has come to resemble a pleasant, well-policed suburb, a little-known neighborhood known as Internet Relay Chat remains the Wild West.

While copyright holders and law enforcement agencies take aim at their adversaries on Web sites and peer-to-peer file-sharing networks like Napster, IRC remains the place where people with something to hide go to do business.

Probably no more than 500,000 people are using IRC worldwide at any time, and many of them are engaged in legitimate activities, network administrators say. Yet that pirated copy of Microsoft Office or Norton Utilities that turns up on a home-burned CD-ROM may well have originated on IRC. And the Internet viruses and "denial of service" attacks that periodically make news generally get their start there, too.

Recently the network's chat rooms were abuzz with what seemed like informed chatter about the Sasser worm, which infected hundreds of thousands of computers over one weekend.

"IRC is where you are going to find your `elite' level pirates," said John Wolfe, director for enforcement at the Business Software Alliance, a trade group that fights software piracy. "If they were only associating with each other and inbreeding, maybe we could coexist alongside them. But it doesn't work that way. What they're doing on IRC has a way of permeating into mainstream piracy."

Last month, the FBI, in conjunction with law enforcement agencies in 10 foreign countries, announced an operation called Fastlink, aimed at shutting down the activities of almost 100 people suspected of helping operate illegal software vaults on the Internet. The pirated copies of music, films, games and other software were generally distributed using a separate Internet file-transfer system, said a Justice Department spokesman, but the actual pirates generally used IRC to communicate and coordinate with one another.

"The groups targeted as part of Fastlink are alleged to have used IRC to have committed their crimes, like almost all other warez groups," spokesman Michael Kulstad said in a telephone interview. Warez, pronounced like "wares," is techie slang for illegally copied software.

When IRC started in the 1980s, it was best known as a way for serious computer professionals worldwide to communicate in real time.

It is still possible -- though sometimes a bit difficult -- to find mature technical discussions among the tens of thousands of IRC chat rooms, known as channels, operating at any one time.

There also are respectable IRC systems and channels -- some operated by universities or Internet service providers -- for gamers seeking opponents or those who want to talk about sports or hobbies.

Still, IRC perhaps most closely resembles the cantina scene in Star Wars: a louche hangout of digital smugglers, pirates, curiosity seekers and the people who love them (or hunt them). There seem to be IRC channels dedicated to every sexual fetish, and IRC users speculate that terrorists also use the networks to communicate in relative obscurity.

It is almost impossible to determine exactly how many people use IRC and what they use it for, because it takes only some basic technical know-how to run an IRC server.

Some Internet experts believe that child pornography rings sometimes use their own private, password-protected IRC servers.

Particularly wary users can try to hide their identity by logging in to IRC servers only through intermediary computers. There are, however, scores of public IRC networks, like DALnet, EFNet and Undernet.

Hackers scan through millions of possible Internet addresses looking for those unprotected computers.