The StopBadware.org coalition, funded by Google, has listed the Kazaa file-sharing application at the top of a list of noxious software programs that present a threat to business and consumer users.

The coalition, which counts Sun Microsystems and Lenovo among its sponsors, will recommend in its inaugural Badware Report that users stay away from Kazaa and three other programs that can be combined with Trojans and bots for use in data theft attacks.

"[Kazaa] does not completely remove all components during the uninstall process, interferes with computer use, and makes undisclosed modifications to other software," the group said in the report, which is scheduled for release on March 22.

In addition to Kazaa, StopBadware.org said computer users should stay away SpyAxe, a rogue anti-spyware program; MediaPipe, a download manager that offers access to media content; and Waterfalls 3, a screensaver utility.

In Kazaa's case, the report said the P2P agent comes bundled with several annoying and potentially dangerous adware and spyware programs, including TopSearch, AltNet Peer Points manager, BullGuard P2P, Cydoor, The Best Offers, InstaFinder and RX Toolbar.

Spyware can do everything from steal your identity to perform corporate espionage. Spyware is installed on your computer, often without your knowledge, to gather information on you.

So, in an effort to get a handle on the growing problem, NYU and Princeton recently gathered experts in law, technology and policy to discuss the state of spyware and what can be done about it.

"What purposes does the Internet serve in people's lives, and in what ways does this threaten them so that we should come down as a society and say, 'This violates what we think is important about the Internet and how we act online?' " Helen Nissenbaum of NYU said. "Hopefully, that will inspire all of these different people to go out and develop solutions in their particular areas."

One of the reasons spyware is so difficult to crack down on is there's still no real agreed upon definition of what it even is. It's like that old argument with pornography -- you just kind of know it when you see it.

"A consumer knows when they have it," Ari Schwartz of the Center for Democracy in Technology said. "Spam is the same way. If you have something on your computer that's doing things that you don't want it to do, it's spyware. It's really a major concern because it's changing the way people use the Internet. Pew did a study showing that about 52 percent of consumers have changed what they do because of spyware."

So while prosecutors and software developers continue to work on ways to protect you, there are several ways you should also be protecting yourself.

"You need to be careful about which Web sites you go to. It's better if you stick with reputable sites," Ed Felten of Princeton University said. "It's good to have an anti-spyware tool, but watch out because some of them are fraudulent. Some of the so-called anti-spyware tools actually have spyware in them, so you want to go to a reputable organization and get advice about exactly which anti-spyware tools to use."

You're also asked to be more vocal. Complain if you can.

"People should say if they see advertising they don't like, start to blame those companies, because right now they only see the benefit of advertising that way and not the harm," Schwartz said.

The good news on the horizon is that many analysts believe improvements in the next Windows operating system, Vista, due out next year, could reduce spyware from the major problem it is today to little more than a minor headache.