1. A method of scanning computer network traffic for viruses, the method comprising: providing a scripting language for creating script patterns that identify network viruses, the scripting language allowing for the use of conditional flow control in a script pattern to identify a particular network virus; creating a first script pattern using the scripting language, the first script pattern comprising a first set of instructions for identifying a first particular network virus; creating a second script pattern using the scripting language, the second script pattern comprising a second set instructions for identifying a second particular network virus, the first and second set of instructions including at least one instruction for conditional branching to skip a next instruction; generating a data stream from network data packets received over a computer network; and scanning a portion of the data stream for existence of the first particular network virus by executing the first script pattern and for existence of the second particular network virus by executing the second script pattern.