Average PC harbouring 28 bits of spyware

US ISP EarthLink is starting to keep score in its fight against spyware.

The internet service provider on Thursday said it found an average of nearly 28 spyware items on each PC it scanned during the first quarter. The company, in conjunction with Webroot Software, conducted a total of 1.06 million scans through its Spy Audit service. The majority of the items found were relatively harmless, EarthLink said, but some represented serious problems.

The term "spyware" has yet to be precisely pinned down. EarthLink uses it to describe several types of software code that might be deposited on a person's computer, often when freeware or shareware such as peer-to-peer programs are downloaded. The most common type, it said, is adware: software that displays ads and also sends data back to a third party. Others include system monitors, which track a computer user's online activity.

"While most spyware is adware-related and relatively benign, it's disturbing that over 300,000 of the more serious system monitors and [Trojan horses] were uncovered. This figure represents how real a threat identity theft or system corruption is for users," Matt Cobb, EarthLink's vice president of core applications, said in a statement.

Consumer groups and lawmakers have expressed concern over the proliferation of such software. The Federal Trade Commission, which has taken action on spam and other internet-related privacy issues, plans a high-profile hearing on the matter on Monday. Utah, meanwhile, has passed a law to curb spyware.

Still, groups such as the Business Software Alliance argue that these laws tend to focus too much on technology, rather than on practices that might need to be curbed.

The Spy Audit service is available to all internet users, not just EarthLink subscribers.

Dinesh C Sharma writes for CNET News.com