I found several circuits for using these encoder and decoder chips with google.
They are intended to work with each other so that when a button is pressed on the encoder the decoder changes an output. They do not need a processor.
If you wish the send other data from one Bot to the other then you don't use these encoder/decoder chips. Instead you send serial data out of the processor into the transmitter to send and out of the receiver into the other processor.
You haven't given us which 433MHz RF modules you are using but I'll guess they are one of the low cost modules. These typically use OOK modulation therefore the serial data should use an encoding method to ensure the serial bits change (no continuous 1's or 0s).
Google the terms:
The UART in the processor can be used if the data is pre-encoded or bit-bang the data output of a port pin.
And here is a link using this type of RF modules on a:http://letsmakerobots.com/node/12336
The VirtialWire code does work very well and is the correct way to send data on these RF modules.