Kaspersky Internet security 2012 is supposed to be a good and safest software. Its good in terms of security but slows down the system completely. Also no patch files for updates. In India there are people still without internet connection but with systems.No Internet? Kaspersky is completely useless.
It uses the system for its own full usage. But has a good url advisor and removable usb scanning. One more big problem with Kaspersky is it boots along with ur OS at startup. So your system may start little faster in case of good hardware configuration.