An April audit conducted by Earthlink and Webroot scoured the systems of some 420,761 computer systems. The audit discovered more than 11.3 million forms of spyware and Trojans installed on users' computers.

In March a similar was conducted on 237,199 computers and found a little over 7 million spyware and Trojan installations. 

"The SpyAudit's popularity shows that consumers want to find out what is on their computers," said David Moll, Webroot's CEO.

Earthlink offers the scanning service to anyone on its Web site. In addition there are numerous other spyware scanners available (such as Spybot Search and Destroy , AdAware , etc) that can be used to detect and remove such nuisances.

Recently, the US House of Representatives Subcommittee on Commerce, Trade and Consumer Protection approved a bill, "The Securely Protect Yourself Against Cyber Trespass Act," which will reportedly introduce fines of up to $3 million to entities who install spyware on users' computers without consent.