How to protect a computer from virus ?

Step1
Be cautious about what disks and files you accept from other people.


Step2
Don't reuse disks that have been in other computers, don't download files from insecure sites, and don't open e-mail attachments unless you are expecting them. Be wary of messages and attachments, even from people you know, with vague subject lines and contents, such as 'Check this' or 'See these pics!!!'

Step3
Obtain an antivirus program to more safely share disks, download files from the Internet and open e-mail attachments.

Step4
If your system gets a virus, visit your virus-scan software manufacturer's Web site and install any virus updates that are available. Then run the software. The software may not be able to delete the virus, but it may be able to identify it.

Step5
Search the Web for information regarding your specific virus by typing the name of the virus or its associated file into a search engine, followed by the word 'virus.' For example, 'Melissa virus,' 'BubbleBoy virus,' and so on.

Step6
Download and install any software patches or other programs that will help you eliminate the virus. Or follow any instructions you find on deleting the virus manually.

Step7
Run another virus scan to make sure the virus was dealt with properly.

Step8
Employ extra caution when you receive attachments that end in the commonly used extensions .doc, .exe, .com, .xls or .ppt. Never open attachments that end in .vbs or .js, since a typical user would never have a reason to open these files.

From : http://www.ehow.com