Karthik77:
I am using the modified version in http://arduino.cc/forum/index.php/topic,118440.0.html and still basically have the same problem
You see the com port but can't use it? are you sure the com port is the arduino? can you open the serial monitor and send something so the RX led blinks in the arduino?
The issue with arduinos is that we don't have like a lot of "error codes", there are few problems, but lot of causes.