I use Norton Internet Security. It cost about $80 
but I didn't get it just for the pop ups.  It's a 
firewall and stops my computer from being 
hacked.  Since I've had it on here, I am amazed 
at how many times my computer comes under attack 
from hackers.  Almost 5-6 times a night.  If you 
don't have a firewall I can almost guarantee that 
you're being hacked.

NIS also comes with antivirus software so it's a 
package deal.  I strongly recommend this program 
to stop pop ups, automatic installs and most 
importantly the hack attacks.

Spybot also found about 30 spy programs on my 
computer.  I was shocked!