Most organizations, whether they be government, commercial or military, are now highly dependent upon their computer systems and networks in order to function. Large amounts of digital data are stored and processed in large computer systems and transmitted between computers linked together in complex communication networks. Without appropriate safeguards this data is susceptible to interception during transmission, or may be subject to various forms of attack whilst in storage or during processing. Computer misuse is seen by many as a growth industry and a serious threat which is frequently undetected and under reported. The threat posed from malicious acts is intangible and notoriously difficult to quantify, and only those incidents which are discovered appear in official statistics. However, it is clear from events which all to frequently do get reported that there is a real danger from unwarranted computer intrusions, whether they be for fun, curiosity or something more sinister. Over the past decade or so, the information security industry has grown into a multi billion dollar business, providing solutions to the perceived threats to data confidentiality, integrity and availability. Cynics argue that the industry has hyped the hacker and information warfare threat out of all proportion in order to sell their products and services. So what then are the main risks to computer systems and from a cost/benefit perspective, what computer security consultancy services offer adequate protection and value for money?