I have downloaded Norton Antivirus and now my pc is slow - why?

Because Norton is one of the biggest RAM drainers and if you are running an older version of Windows like 98, ME, or 2000 or you have an older PC then Norton will really make your computer drag. You also need to think about how long it has been since you reformated (erased) your hard drive as many people do not understand that over time Windows rewrites its self over and over and after a while your computer in general starts to slow because of programs you have installed or uninstalled and Windows in general.

If you have never reformatted your hard drive since you got your PC then I highly recommend doing so which you can do yourself or take it in to Best Buy or any computer store.

Another issue you may be facing with your PC slowing down is you may be infected with a virus, worm, or Trojan Horse. Since many of the viruses, Trojans, and worms of today disable Anti-Virus, Firewalls, and Anti-Spyware software to avoid being detected the only true way to discover if you are infected is to visit an external Web site and use the FREE scanner on your hard drive to make sure. I have created a security site that helps you scan your PC and what to do, plus it helps you verify that you have the right security software installed on your PC. To visit my security site go to: http://www.rrsecurity-abuse.com/virusfix...

I also recommend that you visit this site: http://www.pcworld.com/article/id,130869... from PC World that did an amazing job on reviewing the top AV software makers on many different levels. The 2 AV software vendors that scored the highest on not dragging down your PC was Eset NOD32 and Panda Antivirus 2007. I know you spent money on Norton but I would recommend that you throw it out and start over with something else besides Norton or McAffee. I refer to those two programs as a creeping vine as they get in to everything on your computer which if your hard drive hasnt been reformatted in a very long time, your PC is older, or if you dont have enough RAM then Norton and McAfee will really drag down your PC. I am a Network Security Admin and have spent the past 7+ years researching and testing Security products which is why I created the security Web site in hopes to help to educate others and offer products that are cheap or free. I hope my answer helps.