6. A system for providing computer security, comprising: a non-transitory computer-readable storage medium storing executable computer program modules comprising: a hygiene cache module for receiving from a plurality of clients data describing client hygiene scores for the clients and describing a plurality of web sites visited by the clients, and for storing the client hygiene scores associated with the plurality of clients, the client hygiene score for a client calculated responsive to an amount of malicious software detected at the client; a hygiene computation module for calculating a secondary hygiene score for a web site of the plurality of web sites visited by the clients based at least in part on a number of clients with predominately good client hygiene scores and a number of clients with predominately bad client hygiene scores that visited the web site; and a reputation computation module for calculating and storing a reputation score for a file hosted by the web site responsive to the secondary hygiene score of the web site, the reputation score representing an assessment of whether the file is malicious; and a processor for executing the computer program modules.
6. A system for providing computer security, comprising: a non-transitory computer-readable storage medium storing executable computer program modules comprising: a hygiene cache module for receiving from a plurality of clients data describing client hygiene scores for the clients and describing a plurality of web sites visited by the clients, and for storing the client hygiene scores associated with the plurality of clients, the client hygiene score for a client calculated responsive to an amount of malicious software detected at the client; a hygiene computation module for calculating a secondary hygiene score for a web site of the plurality of web sites visited by the clients based at least in part on a number of clients with predominately good client hygiene scores and a number of clients with predominately bad client hygiene scores that visited the web site; and a reputation computation module for calculating and storing a reputation score for a file hosted by the web site responsive to the secondary hygiene score of the web site, the reputation score representing an assessment of whether the file is malicious; and a processor for executing the computer program modules. 9. The system of claim 6 , further comprising: a client communication module for providing the reputation score for the file to a client that encounters the file.