The best thing to do to protect your computer from viruses is to save your data on separate CDs. It is the best protection against accidental files-removal. To protect your data and avoid your computer to delete them accidentally, shut down your computer properly and never shut down it manually. It is better not to share your software with friends because if you do so, it will be first a violation of copyrights and then it will increase the chance of having a virus on your computer
Always accept when Windows ask you for a scan when you start the computer. A scan always delete files that can damage computers and their protection against viruses. Scan all the files you download from the Internet to protect your computer against viruses or other kind of viruses (trojan horse, malware, cookies). It is better to scan Word file or Excel file before opening them because they may contain one virus which can strongly damage your computer.
Like most people, you probably use Windows for your computer. To protect computers better, Microsoft created 2 tools for Windows: Windows update and Service packs. The first software updates new patches weekly from Microsoft Windows corporation to improve the protection of your computer against viruses. Service packs correct lots of errors that you can find on computers because of Windows. However, the removal of service packs can damage your computer and your data. Anyway, you also have to install a firewall for your computers to protect it from other Internet risks.

A firewall is a software which prevents lots of viruses to enter your computer and delete personal data. A firewall protects your personal files against many damage.
For instance, some viruses, also called “worms” go to millions of computers and the removal of files from these viruses can really harm the protection of your computer. Sometimes, your firewall can block a safe software because it detects it as a virus. In this case, you can still protect your computer by authorizing this specific file to enter your computer because you know the source.
You also have to update your firewall weekly to check for new viruses that are created each day to damage your data. You should run your firewall daily to protect your computer efficiently.

One antivirus software is necessary for the security of your personal data. If you need high level security, scan all the hard disks of your computer each week and update your antivirus software often and not only the day when you scan your computer. New viruses are created daily, so make sure you decide the removal of your files and avoid viruses to do it.
If you fear to download a free antivirus software, you can either buy it from a classic retailer and not buying it on the Internet or you can do a free virus scan at the website of Symantec: http:///security.symantec.com. On the Internet, one single website can really damage the security of your computer so at least, use this website to protect your computer from viruses.

As each website has their own risks, each e mail can gather many different kind of threats such as malware, trojan horses or cookies.
Always scan each mail and its attachment file (Text file, JPG, GIF or MP3) with your antivirus software to prevent your computer from being infected by some malicious programs such as above. Never reply to e mail requests asking you to send your banking account details. Banks never ask you for these personal details on the internet for security reasons. It may certainly be a malware from an illegal website trying to steal you.
Always scan each mail and its attachment file (Text file, JPG or MP3) with your antivirus software to prevent your computer from being infected by some malicious programs such as above.

Msn Messenger is the best way to spread trojan horse, spam, malware or cookies. You have to know that it is very easy to create malicious programs to send viruses through msn messenger and benefit from the security weaknesses. These programs allow people to send you friend requests to give you spam or trojan horse so make sure your friend request comes from someone you know. Scan each file your friends want to send to you with your antivirus software.

A cookie is a tracing file that gathers all information about the way you surf on one website. These cookies are stored in your hard disks. When you come back to the same website, it helps them to know who you are and to promote goods for you even if you do not ask them for. If you use Internet Explorer or Mozilla Firefox, it is easy for you to delete cookies, you only have to delete them from “tools”.

If you receive a mail you did not expected, it is probably a spam so do not open it. If, unfortunately, you open it and the spam ask you to valid your e mail address, do not reply because it is the best means of receiving commercials from the mail-sender. Spams are very efficient programs because it can be very hard to detect them even if you have an antivirus software and even if you update it regularly.

A trojan horse belongs to malicious programs such as spams or malwares. A trojan horse is an executable program which will force the computer to perform some actions. For instance, some trojan horses can block definitely your access to your e mail software such as microsoft outlook. Never download files from unidentified people from an unknown website and beware of hidden file extensions

A malware (malicious software) is a virus programmed to damage your computer. Without an antivirus software, it can be hard to detect and malwares can really damage your computer so it is better to update regularly your antivirus software to be sure it can prevent your computer from the most recents malwares.

These softwares protect your computer from lots of internet threats
Firewall:firewall of windows, ZoneAlarm Firewall (free)
Antivirus: Avast Home Edition (free) , Kaspersky , BitDefender
E mail security: MailWasher (free)
Spams: BullGuard Internet Security (free) , Spam Bully for Outlook Express
Malwares, spywares: Ad-Aware (free), Spybot- Search & Destroy (free)
Trojan horses: Anti Trojan Elite, Trojan Remover