Antivirus software provides an essential layer of protection from a multitude of virus, trojan, worm, spyware, adware, dialer, keylogger and rootkit infections. Traditionally antivirus programs just detected viruses and spyware removers just detected spyware, but nowadays the boundary between antivirus and spyware removers is unclear. Most current anti viruses have at least reasonably good detection rates of all forms of malware. Malware includes viruses, trojans, worms, spyware, adware, dialers, keyloggers and rootkit threats that perform malicious activities on a computer. With the huge increase in malware, antivirus software cannot keep up with detecting all of it. But using more than one real-time antivirus uses much more system resources, can cause conflicts and even reduce protection. So I recommend you only choose one antivirus for real-time protection. Instead, you can increase your protection using other security software.