security newbie

Hi, i just stumbled on this site and am fascinated. i am no pro, self taught and always learning. I recently became more interested in security after repairing a friend's computer that had an email virus- you probably know the one, it cut off the mouse and keyboard after a few seconds. I am always interested in making my pc more protected, i am running an M$ MN500 wireless base station to my PC, laptop & xbox. My PC has NIS2002 and i am updating to NAV2004 in janurary. i thought that between the router and NIS that i would be secure but reading some of your threads i am really beginning to wonder ...