Yes you can, Webroot was designed To be a true companion , if it detect another AV, it will give priority to the other one. @Malware1: as said Nvt the distinction between malware and virus was true 20 years ago , defined by their behavior. Viruses (worms, etc...) are those who infect a file then spread to others Or not. Malwares were mostly trojan horse, keyloggers, remotecontrollers and other backdoors. At that time antiviruses and antimalwares were specialized in their own field but now the term antimalware is obsolete since AVs detect malwares and is used just for a marketting point. Now all Avs are de facto antimalwares.