Many computer viruses are stuck to websites, some on email, and in programs. Viruses do things like doing nothing to multiplying and taking up memory to erasing your entire hard drive.
Here is a list of the precautions I take to avoid computer viruses
1. Use an Internet Firewall and install Anti Virus software
2. Install Spyware detection software
3. Never open an email attachment from someone you do not know
4. Keep your computer with the latest update
5. Be careful with the pirates software
6. Use pop-up blocker on your Internet Browser
7. Open your eyes!
List of Free Anti Virus Software
1. AVG Anti Virus
2. Trend Micro
3. Avira