Get all that was mentioned above, I have 4 different anti-spy programs active on my computer.
One of them is a trojen remover, and the other one has a free trial that expires soon. So acually I have two: Spybot S&D, and Ad-Aware.
They work wonders together, one picks up what the other one misses.
Also Symantec Norton Anti-Virus (Not Free) takes out some spyware, but most of the time it can't remove it completely.
If you are Using Microsoft Internet Explorer, get
Mozilla Firefox. Because spyware tends to stick to IE, especially if you have MS Windows.
But if everything gets out of hand, reformat your computer as a last resort. I had to reformat after the invasion of the dreaded IE plugin "Elite Toolbar."