I use Mozilla. It's free, it's easy, and it has nifty features that Internet Explorer and Safari (my other two browsers) don't have, like the tab feature. It automatically blocks popups and you can right-click and block ads you don't want to see...
Unless, that is, the ads are done with the graphics animation program Flash. Those I cannot figure out how to block, and--even worse--they're the ads I *really* hate. LIke all the DNC "Help remove Bush from office" ones (not that I'm a Bush fan, I just hate their ads).
Grr. Stupid flash.