1. A method of updating a plurality of computers, the method comprising: creating in an update source, a first message comprising a one or more instructions and an address of a message repository; transmitting the first message to a first computer using a Push or a Pull protocol; transmitting a second message to the first computer using the Push or Pull protocol, the second message comprising data retrieved from the address in the first message; executing in the first computer, a one or more of the instructions in the first message with at least some of the second message; updating the address in the first message to match the address of the first computer; transmitting the updated first message to a further one of the computers; and repeating transmission of the second message to further ones in the plurality of computers and executing and updating until substantially all of a pre-defined number of computers have been updated, wherein the executing and updating are accomplished with the respective further one of the computers rather than the first computer.