My recommendations, FWIW...
webwasher. It's a great ad and popup filter that stops everything in every version of IE that I have used from 5.0 up to the current 6.1.
Fobotsco wrote
Just occasionally a pop-up is intentional and required; for instance when you are looking at a product in a Commercial Web-Site on-line catelogue and request more information about the product. Do these pop-up killers stop those as well?
Filters that disable the unwanteds in a website will in all probability disable some of the wanteds. In removing the c r a p, Webwasher will interfere with some desirable functions of a website, but it is easily customiseable as to the degree of filtering and is also easily switched on and off as required. It is free to non-commercial users. I cannot recommend it highly enough.
At the risk of loading up the 'puter with background tasks (I take your point, Fobotsco, but I'm not a power user and my new PC has enough grunt to cope with the overhead) I also use
Pest Patrol,
Zone Alarm Plus and
PC-Cillin 2002 all running concurrently in the background.
(Just to top it off, my ISP does optional serverside virus screening and Baysian spam filtering, which I tidy up with
Mail Washer.)
Edited to add...
I used to use
AdAware occasionally to screen for adware, but found
Spybot Search and Destroy to be more comprehensive and more frequently updated.
Cheers
AA