It is important to have an updated version of anti-virus software installed in your PCs to scan and detect the presence of any virus. They look for patterns in the files or memory of your computer that indicate the possible presence of a known virus. Anti-virus packages know what to look for through the use of virus profiles (sometimes called signatures") provided by the vendor. Anti-virus should be updated with latest virus definitions or the anti-virus should support automatic updates in order to detect new viruses since new viruses are discovered daily. List of well known anti-virus vendors,  everyone who uses the net to download should have anti-virus software . 

 A Trojan horse detector is also fairly important and most anti-virus software can detect Trojan horses. Various  Trojan horse detect program are available here and can detect and remove trojans in your computers. Other such programs are Netbus Detective which detects all incoming netbus activities and remove any trojan horses attributed to netbus. Jammer is a scan detector and registry monitor. It also stops varieties of Back Orifice and Netbus before they can be installed into a system and for any suspicious change detected to the registry (such as the introduction of a trojan) it will ask whether or not to allow the change. If not, Jammer will delete the program daily and can detect and remove trojans in computers. Other such programs are Netbus Detective which detects all incoming netbus activities and remove any trojan horses attributed to netbus. Jammer is a scan detector and registry monitor. It also stops varieties of Back Orifice and Netbus before they can be installed into a system and for any suspicious change detected to the registry (such as the introduction of a trojan) it will ask whether or not to allow the change. If not, Jammer will delete the program. 

Safe Email Practices 

A general practice is not to open unknown email attachments. Before opening any e-mail attachments, be sure to know the source of the attachment and if you need to open it, you need to disconnect your computer's network connection, save it to your hard disk and run a virus scan with an updated anti-virus, enabled to scan all files on the attachment. It is not enough that the mail originated from an address you recognize. Be cautious that malicious code can be distributed in amusing programs with attractive subject headings, such as the recent W32 SIRCAM worm, discovered in July 2001 which comes in attractive subjects and is a temptation to any users to open the attachment. 

Avoid sending messages with attachments that contain executable codes, like Word documents with macros, EXE files and ZIPPED files. You can use Rich Text Format, or RTF, instead of the standard .DOC format. RTF will keep your formatting, but will not include any macros. There is, however, a couple of viruses out there that will fool Word when you save as RTF, so while you cannot completely trust .RTF files it is still a good practice. This may avoid the embarrassment of you sending them a virus if you are already infected. In Microsoft Word 97, enable ‘Macro Virus Protection” by choosing: Tools --- Options --- General and select the appropriate checkbox. Do not open unknown programs. Home users are advised not to open any unknown programs unless it is authored by a trusted party. Also, don't send programs of unknown origin to friends or colleagues simply because they are amusing – who knows, they may contain a Trojan horse program. 

Disable hidden filename extensions 

Windows operating systems contain an option to "Hide file extensions for known file types". The option is enabled by default, but you can disable this option in order to have file extensions displayed by Windows. After disabling this option, there are still some file extensions that, by default, will continue to remain hidden. There is a registry value which, if set, will cause Windows to hide certain file extensions regardless of user configuration choices elsewhere in the operating system. The "NeverShowExt" registry value is used to hide the extensions for basic Windows file types. For example, the ".LNK" extension associated with Windows shortcuts remains hidden even after a user has turned off the option to hide extensions.