Apart from getting data from the internet, what will the standalone boards be doing - for example what I/O capabilities will they need?
Have you considered using the PC to get all the data from the internet and sending it to the Arduinos - which could then do stuff with the data and send other data back? IMHO it is much easier to interface with the internet using a PC program. And you could use cheap nRF24L01+ modules to act as the wireless links between the 3 standalones and the hub. I am assuming the hub will be connected to the PC with a USB cable.