system
10
I think you will be better serviced with Avast (even the free version).
The core protection is more solid, and there will be no system slow downs.
But, it won’t be enough. No one solution is.
You could: add extras to your browser (hopefully Firefox):
https://addons.mozilla.org/pt-PT/firefox/addon/adblock-plus/
https://addons.mozilla.org/pt-PT/firefox/addon/noscript/
https://addons.mozilla.org/pt-PT/firefox/addon/wot-safe-browsing-tool/
https://addons.mozilla.org/pt-PT/firefox/addon/betterprivacy/
https://addons.mozilla.org/pt-PT/firefox/addon/ghostery/
Or you could go further and use a radical solution like a FW/HIPS:
http://www.online-armor.com/
http://www.comodo.com/home/download/download.php?prod=firewall
All of the above will work peacefully with Avast.
Or you could go with Avast IS.