Peter,
I prefer Malware Bytes to AdAware. Use the free version.
Needs to be run manually, but does a very good job.
I have used AdAware in the past on one desktop and a laptop we have. It finds mostly tracking cookies. Since you have McAfee I'm guessing you wouldn't need both but having more than one won't hurt anything as long as they don't scan at the same time, which would slow down preformance. But like the other replies I really like Malwarebytes, I've used Malwarebytes to remove several infections.
Is Malwarebytes compatible with McAfee ? Will it slow down the computer at start up because my computer is already slow enough especially since I installed Skype ?