You might be ale to get one of these "Flash" places to do it, but Sprint (Virgin is a Sprint MVNO) uses different 3g data channels so the data would not work.
Cricket seems to be the cheap carrier of choice since they buy from Verizon, but again I think things like MMS don't work and there's something else that does not work but it escapes me at the moment.
You can still use it as a Wi-Fi device, just remember that it can still dial 911 even when deactivated.