Virtual Wire Control
Unless I misunderstood the question, it should be as simple as extending the code where you print out what's in the buffer with some if-then statements.  For example your code:

for (i = 0; i &lt; buflen; i++)
{
    Serial.print(buf[i], HEX);
    Serial.print(" ");
}


goes through the received string and prints it out bit by bit.  If, instead, you want to know if you received an "A", you can use:

if (buf[0] = "A")
{
  //flip bits here
}


You could also use a Case-Switch block to define several letters.  There are many ways to improve this code, including using strcmp so that you can send full words and not worry about case or terminations, but it's best to worry about that once you're off the ground.

If I misunderstood the question, I apologize.  I'll be glad to try again with more information.