Viruses:
Worms-worm differs from a computer virus in that a computer worm can run itself. A virus needs a host program to run, and the virus code runs as part of the host program. A computer worm can spread without a host program, although some modern computer worms also use files to hide inside.
Trojan Virus-Trojan horses are designed to allow a hacker remote access to a target computer system. Once a Trojan horse has been installed on a target computer system it is possible for a hacker to access it remotely and perform various operations. The operations that a hacker can perform are limited by user privileges on the target computer system and the design of the Trojan horse.
Heur/Malware-a malicious file or program that gets onto your system by pretending to be benign or desirable
to protect your computer try this tools:


Antivirus:
Top 5 Free Antivirus Software
1.Avira Antivir

2.Rising Antivirus

3.Avast Antivirus

4.Comodo Antivirus

5.AVG Anti Virus

Hope i Help....






