Are popups scams?

For my A level ICT I had to give a talk about the importance of Internet safety and pop ups was an area of major concern. Popups that say you have won a prize can do 4 things, maybe altogether, maybe one or two.

1. It is totally genuine and you DO win a prize. Chance of happening 0.0000000000001%
2. It is a scam designed to collect personal data for advertising agencies. Information such as address, name, shopping habits etc can all be sold off to large firms, and you may end up the target of a lot of spam, either virtual or real.
3. It is a virus. The most common virus downloaded from popups is an extension of the virus trail .ezula.exe (From me research anyway) Ezula virus is a virus that resets your computer as soon as you log in, which means you can only start up windows if your all up for wiping the disc.
4. Its spywear that is already installed on your PC that is redirecting spam websites because its what they spywear program is telling it to do. Run Search and Destroy and see if that is the problem.

My advice? Run a pop up blocker and a GOOD anti virus. Youll be a safe safer within no time ^.^