ad-aware is good. Droping some money on spyhunter is also a good choice, but if you have internet explorer, or are searching porn. these would be your two major problems. try downloading ad-aware, and download mozilla, as your search engine, which is a pop up blocker. that helped me atleast. Go to www.majorgeeks.com for your ad-aware, but again this wont help that much if you have IE,but will get rid of a majority of your spyware for free
http://www.downseek.com/directory/108.asp
There is a variety of free and useful anti-spyware programs. Ad-aware 6.0 works well along with BPS spyware remover. If you use windows, you can check for trojans or background files that are corrupt with a windows task manager scanner that scans your processes at http://www.neuber.com/taskmanager/
Hope this helps, good luck.👆