I've posted an article in eZineArticles.com called Keeping Your PC Safe From Spyware. Here's the lead-in of that post:

Broadband Internet truly has been an amazing equalizer, allowing mom-and-pop shops to compete with the big boys on Madison Avenue. It's also brought streaming audio and video, rich content, and almost-instant connectivity to friends and family across the globe. It's also brought its share of pain to the party in the form of spam, adware, viruses, spyware, and other malware.

The keys to keeping your PC safe from spyware is three-fold:

1. Detection. You have to know whether spyware and other malicious code, also known as adware and malware, has infected your PC. Liken this to cancer treatment: Unless you about its existence, you just feel sick.
2. Removal. You have to excise the cancer, or else it will spread.
3. Prevention. The last step in fighting cancer, and spyware, is prevention. Once, you've gotten rid of all the spyware, you can take steps to inoclulate your PC against recurring infestations.

The best way to accomplish all 3 steps in one fell swoop is to install an anti-spyware program, like Ad Aware Pro, Spyware Nuker, or Spyware Doctor. These are the creme of the crop; they are designed from the ground up to detect, remove, and protect against spyware, adware, and malware of all sorts.