A MAC with the Safari web browser (has a box to check for stopping pop-ups).
As recommended by anaother poster, Spybot: get all the hidden links (really Trojan horses).
On Windows. Go into Control Panel, Admin. and disable Messenger - a lot of the more aggressive pop ups use that feature and truly take over the machine.
I could rant about how the idiots took over computers. The stupid kid (of all ages) customers who grew up in, and think this still is, a cartoon world. So, you have all the cheezy but busy and crazy graphics which suck up bandwidth, overload and slow everything down, and are quite useless. When Microsuck stopped supporting run-time Windows, that's when their insidious take over and control of the industry truly began. Sure, there are needs for graphics - SOMETIMES AND WHEN NEEDED - and they started a common interface instead of the hodgepodge. Then, they imposed their junk on everyone. And, the computer manufacturers loved it - could sell more and more hardware which was now necessary (I had a wonderful IBM -P70, I think it was, the one that was portable and an attache case, 386 processor, with DOS and Desqview386 it was just fine. But, no, not for all the "great" new junk.). So, this leads us to stuff like Java, great on paper, and apparently functional, but allowing every charlatan to take over our operating systems and machines. HUMBUG. <rant over>