In addition, some spyware installs itself (“drive-by installation”) using Active-X controls in Internet Explorer. All you need to do is visit an infected web page and you’re infected.
That’s why I recommend everyone use Spyware Blaster. It prevents that sort of thing.
You also have to be very conscious of security when you’re browsing.
Another good reason to use more security-minded browsers like Opera or Mozilla.
Read license agreements carefully, too, and be careful of wolf-in-shepherd’s-clothing programs like Spyware Nuker which is actually decoy program that makes use of Spybot’s database of adware to do a scan, but then asks you to pay up before actually doing anything about the detected spyware.
The punchline? Spyware Nuker itself installs spyware, which it will of course leave intact even if you pay for their unlicensed and illegal version of the (free) Spyboy Search&Destroy to remove their competitor’s spyware. It’s a data-mining tool of a spam-delivery company called Trek Data.
Evil! Impolite and evil!