Natalia Rudiak of Carrick could not figure out why her trusted laptop was acting sluggish and sometimes unresponsive. Then it crashed, and she was forced to find the culprit: 360 pieces of spyware that could allow cybercrooks to snoop on her computer.

		On the Net AOL/NCSA Online Safety Study, in .pdf format

"You think that you are downloading something good," said Rudiak, 25, who unknowingly downloaded a "Trojan horse" virus. "Instead you are just letting in someone's who's spying on you."

She's not alone.

A report released yesterday by America Online and Washington-based National Cyber Security Alliance, a nonprofit group, found that while most Americans keep sensitive personal information on their PCs, they aren't very savvy about keeping their computers secure.

The study revealed that of the 329 broadband and dial-up Internet users surveyed in 12 states, 77 percent believed their computers were safe from online threats and most had no firewall protection, did not frequently update anti-virus software and had lots of spyware and adware floating around in their systems.

Spyware, which broadly refers to programs that let advertisers track a computer's activities, can allow hackers to steal or transmit information. Spyware also can gather information about e-mail addresses and even passwords and credit card numbers.

Four in five users had spyware or adware programs on their computers, and 89 percent of those whose computers were infected said they did not know the programs were on their computers, the study found.

The study reported that over half of those surveyed didn't understand the difference between anti-virus software and a firewall -- software or hardware that protects outside users from entering the system -- and 90 percent said they did not know what spyware programs do.

"Extrapolating the percentages in our survey, this indicates that millions of Americans are at risk and are already infected by viruses, spyware and adware,'' said Ken Watson, chairman of the National Cyber Security Alliance, an organization that educates consumers and businesses about cybersecurity.

When researchers visited participants' homes Sept. 15 to Oct. 8, to see how safe their computers were, they discovered that most [85 percent] had anti-viral software, but that had not recently updated it.

That alarmed Dena Haritos Tsamitis, director of outreach and education at CyLab, a Carnegie Mellon University initiative created to boost awareness of cybersecurity issues.

Internet users should update anti-virus software weekly, if not more often, to ward off hackers and other cybercrooks, she said.

Prior to her computer going kaput, Rudiak said she never had installed software to ward off uninvited guests.

Tsamitis noted that fending off spyware for your average PC user can be tricky.

"You can download spyware without even realizing it," she said.

And hackers are getting smarter about how they fool PC users into clicking on a link that could make their PCs vulnerable. Some have gone so far as to create pop-up ads that lure users in by posing as downloads of free anti-viral software.

The spyware then camps quietly in a computer collecting information on what Web sites the user visits, even collecting personal data and then funneling it back to hackers.

While most people know what spyware is, the study showed that they weren't sure how to ward off cyber-intruders. Over 60 percent said that they did not use a firewall.

Most dangerous, according to Tsamitis, is the 15 percent of computer users surveyed who didn't have any anti-virus software installed on their computers at all.

That is not only harmful to users' own PCs, Tsamitis said, but it can also be destructive to the global online community.

Unprotected machines, she said, can be used as a weapon to attack other computers without the protection of firewalls and regularly updated anti-virus software.

"That's a simple step that users can take to protect themselves," said Tsamitis. "Honestly, it literally takes seconds to make sure you have the latest protection."

Rudiak's computer is working again, thanks to the help of a Duquense University student. Now she is diligent about updating her anti-virus and anti-spyware software at least twice a week.

"It's kinda cool because you get to see who's been lurking on your computer," she said.