W3C HTML Validation within my HTML editor

Hi, I have developed a text/html editor, and I would like to implement a
feature enabling the user to validate the file he is currently working
on my submitting the local file on his harddrive from an url. How will
my approach be?
 
I tried this without success :
http://validator.w3.org/check?uploaded_file=c:\my_local_html_file.html
<http://validator.w3.org/check?uploaded_file=c:\my_local_html_file.html>

 
1. Is it possible to do this?
2. Am I allowed to do this, or will this be in conflict with your
copyrights?
3. Or are there any other way to do this?
 
You can download this editor from http://www.evolvededitor.com
<http://www.evolvededitor.com>  100% FREE, and 100% commercial fraa as
well.
 
 
Keep up the good work!
 
 
Regards,

David Gabrielsen 
Senior Consultant 

StreamServe Norge AS, 
Karihaugveien 89 
N-1086 Oslo, Norway 
+47 22 90 74 40 Phone 
+47 22 90 74 41 Fax 
+47 92 26 18 54 Mobile 
david.gabrielsen@streamserve.com