The 1997 Virus Prevalence Survey of the National Computer Security Association (NCSA) revealed that macro viruses can cost an organization more than $13,000 per month. Some of the most important factors to consider when purchasing antivirus software are which files are scanned, how often they are scanned, whether the scanning is transparent to the computer user, whether it affects performance, and whether it generates a warning message and activity log. Other factors include how the software is managed and updated, what platforms it supports, and how much it costs. Useful resources for security managers are the two well-known antivirus product testers: Virus Bulletin (VB) and the NCSA. VB is recognized as the industry benchmark for measuring virus scanner accuracy. The NCSA certifies virus products based on VB's In the Wild List. Chart