Those kits use a encoder decoder chip , the sc2262 , sc2272 .
They arnt designed for sending hi speed data, but are more intended for simple on / off type functions where the data to be sent is very small and can be sent at a very low baud rate, such as garage door openers or Rf controlled wall switches.
They wont work with virtual wire , unless you somehow bypass the encoder decoder chips and just use the raw transmitter data input , and the raw receiver data output.
If you read the spec sheet on the encoder decoder chips , you should be able to work out what the maximum data rate is , but it will be very slow , less than 50 bps.