1. A method, in a data processing system, for configuring a data flow filtering mechanism that filters data flows to a plurality of client computing devices, comprising: establishing one or more portions of configuration information for the data flow filtering mechanism that are modifiable by a protected client computing device in a plurality of protected client computing devices and one or more portions of configuration information for the data flow filtering mechanism that are not modifiable by the protected client computing device; receiving a request from the protected client computing device to modify a portion of configuration information for the data flow filtering mechanism that is established as a client computing device modifiable portion of configuration information; storing a client computing device configuration profile incorporating the modification to the client computing device modifiable portion of the configuration information, wherein the client computing device configuration profile is used by the data flow filtering mechanism to filter a data flow to or from the protected client computing device; determining if there is a conflict between a security policy/rule in the client computing device configuration profile and a security policy/rule in default configuration information; and resolving the conflict based on a security policy/rule conflict resolution policy.