The Hidden Money Trail

Spy-Free Computing

These steps can help keep spyware and unwanted adware off your system.

Use firewall and antivirus software: Antivirus tools may be able to prevent an accidental installation. A firewall, such as ZoneAlarm, that watches applications can notify you if an adware program decides to phone home--and can put a stop to it.

Use Internet Explorer only when absolutely necessary: ActiveX makes IE vulnerable to some drive-by installations. Alternative browsers, such as Firefox or Opera, don't use it.

Avoid sketchy sites:Certain kinds of Web sites--particularly some that offer hacking tools, free spyware scans, porn, and the like--tend to attempt drive-by installations.

Check the EULA on each download: Beware of EULA references to "third-party applications" that download advertising or their own updates.

Spurn "warning" pop-ups: Ads that look like a Windows dialog box and warn that you have spyware installed are just slick come-ons designed to lead you to sites that actually install spyware. Instead, use a known spyware remover--like the ones we review in "Best Defenders."

A PC World Special Report

The New Security War: See the Complete Special Report
Best Defenders and Spyware Sweeper Leads the Field (chart)
The Hidden Money Trail
Privacy in Peril
Is the Net Doomed?
Threat Alert: Spear Phishing
Threat Alert: Antivirus Killers
Threat Alert: Instant Messaging Attacks
10-Step Security
Security by the Numbers
More Security Resources on the Web

Also See Our In-Depth Online Series
Web of Crime

PC World Contributing Editor Dan Tynan is author of Computer Privacy Annoyances (O'Reilly Media, 2005). Tom Spring is a senior reporter for PC World. Senior Associate Editor Andrew Brandt also contributed to this story.

Subscribe to the Best of PCWorld Newsletter