Do you know how to get your data from the arduino ?
if this is working writing to a text file is possible using

createwriter to write to a txt file like you would print it to the processing console http://processing.org/reference/createWriter_.html

or see these examples :
http://processing.org/learning/topics/savefile1.html
http://processing.org/learning/topics/savefile2.html

getting the time is possible by useing hour(), minutes() etc:

likethisS:
 int s = second();  // Values from 0 - 59
 int m = minute();  // Values from 0 - 59
 int h = hour();    // Values from 0 - 23
 int d = day();    // Values from 1 - 31
 int m = month();  // Values from 1 - 12
 int y = year();   // 2003, 2004, 2005, etc.

reading serial data is maybe not the easiest thing to start with. so try to do it step by step.  first get the data and print them to the console to see if you get something at all. if this is working you can add the save to txt part...

you can start here : http://processing.org/reference/libraries/serial/Serial.html

http://processing.org/reference/libraries/serial/

Hi blindfish & Cedric,

Thanks for your pointers and book recomendations - I am going to order Making thing Talk - loosk great.

I have now cobled based on the examples etc together some code but fear some basic errors - would be great to hear your thoughts

Code:

import processing.serial.*;
PrintWriter output;

Serial myPort;  // The serial port

void setup() {
 
output = createWriter("data.txt");
  // I know that the first port in the serial list on my mac
  // is always my  Keyspan adaptor, so I open Serial.list()[0].
  // Open whatever port is the one you're using.
  myPort = new Serial(this, "COM6", 9600);
}

void draw()
{
  while (myPort.available() > 0) {
    String inBuffer = myPort.readString();   
    if (inBuffer != null)
	output.println(inBuffer);
	
  int d = day();    // Values from 1 - 31
  int m = month();  // Values from 1 - 12
  int y = year();   // 2003, 2004, 2005, etc.
  
  output.println(d,m,y);
  output.println(d,m,y);    
	
  }

  void keyPressed() { // Press a key to save the data
  output.flush(); // Write the remaining data
  output.close(); // Finish the file
  exit(); // Stop the program
}