Trojans can erase your disk, send your credit card numbers and passwords to a stranger or let others use your computer for illegal purposes like denial of service attacks, crippling networks for months. Just like the original Trojan Horse that was built by the Greeks, the Trojan Horse Virus for your computer is actually something unwanted concealed within something that seems good and positive. Like sharks in a feeding frenzy, these hacker mercenaries view Instant Messaging clients as their personal bank because of the ease by which they can access your computer via the publicly open and interpretable standards. They unleash a Trojan horse, virus, or worm, as well as gather your personal and confidential information, and sell it to other criminals.

Many major operating system vendors have automatic update services. Many hardware vendors and other software packages have followed this trend, incorporating automated update services into their products. In some cases, the services for automatic updates run as the local "system" account. This account has the ability to access and modify most of the operating system and application environment. If this update service can be infected than millions of computers can be infected quickly. Hackers riding piggyback on viruses have only a short window of opportunity to maximize their gain before the viruses are detected, neutralized and logged into Virus Definition databases, 'vaccinating' the system against those strains. Without continuing system vulnerability caused by virus infection there is little they can do to further their malicious ends like stealing personal information, credit card details and other sensitive and vital data.

Many fine examples of Spyware, Trojan and Worm removal software are available, but you must be careful you only download a reputable programme from a reputable site. This is even more important when using free or evaluation software. This is one way that your system can be given a Trojan, through software downloads and installation and obviously the software will not protect you from its own malicious imbedded Trojan.

Because Instant Messaging operates on peer-to-peer (P2P) networks, it spawns an irresistible temptation for malicious computer hackers. P2P networks share files and operate on industry standard codec (encryption codes) and industry standard protocols, which are publicly open and interpretable. Most anti virus software does not incorporate protection for Instant Messaging services.

There is anti-Trojan software that specifically serves to get rid of Trojan Horse virus types, and in most cases it is this type of software you will want to use. You need to be protected against the most common way that users are infected with a Trojan program being through the spreading of it through emails. The sender will send it to the recipient within an email attachment that might say something like "complementarytickets.jpg" or something along those lines that will make you curious and open the file. Another increasingly popular way that Trojan Horses have been spread to users is through the ever-increasing instant messenger programs such as Yahoo Messenger, AIM, ICQ, MSN messenger, and IRC. The one key to remember about Trojans is that they have to be triggered by some mechanism and will not spread themselves. For example, you can have one in your email but you do not open the link then it will not infect your system.

In today's online environment it's important to know what risks lie ahead at each click. Every day millions of people go online to find information, to do business, to have a good time. We've been warned lots of times about stealing data -- identity theft, phishing scams and pharming; we have at least heard of denial-of-service attacks and "zombie" computers, and now one more type of online attack has emerged: holding data for ransom.

So in summary what do we need to do? Well we need at least one constantly updated anti-virus programme from a reputable source. It must be specified and configured to detect and remove virus, spyware, Trojans, and worms. We all need to be more careful when opening emails from unknown senders and most of all, only download from trusted sites.