no solutions i'm afraid but a few comments.
The Cricket system runs on TinyOS, which will only work with Linux.
the Cricket firmware runs on TinyOS but this is all on the actual Cricket module. TinyOS is nothing to do with Linux. it is a RTOS for embedded processors.
the Cricket module can communicate with a host computer over RS232 and as you know what control codes it sends over the RS232 link you can control it from any OS you want.
if you don't know much about RS232 already take the time to read about it now.
try connecting 2 laptops together using serial ports and type data from one terminal to the other.
learn how to use hardware flow control.
trust me, it is simple once you have done it once and getting familiar with the basics will save you a lot of time later.
RS232 over wifi sounds like a nightmare to me. they are 2 completely different ways of transferring information so the process of converting on to the other would be very wasteful. this is only my opinion though. i have never looked into it.
you can connect as many serial ports to a Linux machine as you like within reason. 42 RS232 ports is easily possible.
i have no idea if this is possible on windows or not.
Is there a way to use one transmitter to communicate with all of these ports?
no simple way i can think of.
the problem is RS232 has no addressing so no way to send to just one individual base station.
so, if i was doing this and it had been decided to definitely use your chosen motor controller and Cricket sensor and that one central laptop was to control everything
i think i would be looking for some way to make the robots addressable so communication from the PC can be initiated to only one of the mobile platforms at a time.
try reading up on XBee RF modules. http://www.digi.com/products/wireless/point-multipoint/xbee-series1-module.jsp
with a little circuitry one could be connected to your PC serial port.
the modules are pair-able so in theory the address on the PC connected one could be changed to communicate with a particular remote device.
i don't know how easy (or quick) it is to change the address while the XBee is in use though.
i *think* the XBees also have GPIO pins so you could use those to enable communication to either the Cricket or the motor controller.
an alternative (but Ugly) method would be to find RF modules that can pair with each other and have enough bandwidth to allow 42 pairs and just attach 42 of them to 42 USB-Serial dongles attached to your laptop.
i think the XBee would be capable of doing this as well. you would certainly need something with high bandwidth to allow 42 channels open. 2.4GHz would be the most likely frequency for a successful solution.