1. A virus scan system, comprising: a full scanning system for performing a full scan of each file in a file system; a file inventory system for inventorying each file in the file system and generating a set of inventory records, wherein each inventory record includes a unique key associated with each file in the file system; an inventory compare system for comparing a current set of inventory records with an existing set of inventory records to identify files in the file system that were modified since the existing set of inventory records was generated; and a selective scanning system for selectively scanning only files in the file system that were identified as modified by the inventory compare system.