Validation MarkUp local file

Dear sir or madam,
 
If I validate file
http://www.sukl.cz/cs21vzdelcentr/cs21vzdelcentr2003.htm result is that
the page is valid XHTML 1.0. Strict. 
 
But if I validate the same file in my computer, the result is 

File: 
C:\Work\cs21vzdelcentr\cs21vzdelcentr2003.htm
Sorry, I am unable to validate this document because on lines 1-2, 8-41,
47, 50 it contained one or more bytes that I cannot interpret as
us-ascii (in other words, the bytes found are not valid values in the
specified Character Encoding). Please check both the content of the file
and the character encoding indication. 
This page is encoded in charset=windows-1250.
 
Could you advise me please how I can validate HTML pages in my local
computer?
Thank you.
 
Best regards
Monika Maskova