I wanted to send out a huge thank you to Shaba at the Spybot malware removal forums for helping me to clear up a frustrating adware infection on my work PC over the past two weeks. These folks spend an enormous amount of their free time helping people clear up challenging infections. It may take a bit of time to get their help (they get a lot of help requests!), but when you do, they are knowledgeable, friendly, and professional.
And before you ask, my PC was well protected with a variety of defenses--I know exactly how I got infected, and it was because I was being stupid. :)