from your unique, traceable Internet location--and slow your Internet performance down at the same time.

Those whose wireless systems can be penetrated are exposed to other serious threats too, Powledge pointed out. For example, attackers could implant malicious programs, including spyware, adware and Trojan horse applications, directly onto a computer. That could open the door to more serious problems such as online fraud or even identity theft, he said.

In one instance, a Los Angeles man pleaded guilty in September to distributing pornography spam e-mails, sent out using other people's Wi-Fi connections, which he accessed from inside his car. And in 2003, a man in Toronto was arrested for downloading child pornography using other people's unsecured wireless networks.

The practice of cruising around town to look for unguarded wireless networks has become so popular that the phenomenon has even