This is just a guess
I am using the SoftwareSerial library that comes with the IDE.
I can see that by turning on verbose output:
(File->Preferences_>show verbose output during compilation)
I looks as if you have installed a second SoftwareSerial in your scketch library folder so you end up with two.
C:\Documents and Settings\dad\My Documents\Arduino\libraries\SoftwareSerial/SoftwareSerial.h
Try to delete this (or rename it)
sketch_nov20a:23: error: 'X' was not declared in this scope
This error i because X should be x (not capital)