If you really hate popups - who doesn't - then there is a very easy way to disallow them - no need to download anything at all. Let me show you how to control your popups, and not let your popups control you.
Internet Explorer Users:

1. Under the tools menu, go to popup blocker popup menu and turn on IE's popup blocker if it isn't already
2. Again, go to the same menu, but go to popup blocker settings
3. Under the filters frame, change the level to high.
4. You will now have a popup free browsing experience. If you need to open up a popup on a place such as newgrounds, press the control key(Ctrl) before clicking on the link. This will allow you to open up that popup and only that popup.

Opera 9 Users

1. Press Ctrl + F12 to bring up the options dialog
2. Under the choose how to handle your popups frame, change it to block all popups
3. You now have a popup free experience. If you need to open up a popup on a place such as newgrounds, click the link and then click the popup blocked notice on the upper right corner of the browser to open that popup and only that popup.

Firefox Users: You cannot completely disallow popup windows like in Opera or Internet Explorer. Instead, you must disable Javascript's ability to open windows.

1. Under the tools menu, click options.
2. Move to the content tab
3. Uncheck the enable javascript box
4. You should have a popup free experience, though you have block the ability to have popups at all.

This is a very nice tutorial on how to block pop-ups on the various internet browsers. The internet explorer pop up blocker only works on the newest version though, but I've found it works well.

I've got the google toolbar installed on my internet explorer, and I've enabled the feature on there to block pop-ups. I quite like it and find it does the job well, although i don't think it can be configured as much as the internet explorer pop-up blocker.

Whether you use an addon containing a pop-up blocker or whether you use a pop-up blocker installed in the internet browser by default, it pays to have it set up correctly so that those sites chucking adverts at you, which may contain viruses are blocked from appearing.

There are some sites that can go through the blocker though. The safest thing to do is remove dynamic content like flash, java, and ActiveX which can open URLs around many popup blockers, including IE's.