Waddaya know, a subject on which I actually have some knowledge. Spybot search and destroy is good but I have found that it is best to run a second program called adaware. You can download adaware here:
http://www.download.com/3000-2144-10045910.html?part=69274&subj=dlpage&tag=button just copy and paste that into the browser address window. For both of these programs you need to "update" the definitions file. In Ad Aware, click on check for updates now before you run the program. Then you will need to put a check in the box beside all of the problems that adaware found.
With Spybot click on the check for updates button before running the software. When it finishes you will need to click on fix problems.
For the run of the mill popups that you may get on normal websites like Foxnews or CNN, you can download the Google Toolbar from toolbar.google.com and click on download.
