Regd: Processors and Validating am XML document

I'm thinking of to translate an XML document into an
WML document using XSLT.What i have with me is a
WELL-FORMED XML document.
Is it necessary to validate the XML document before
applying the XSLT to the XML document.
Another help i request from u people is 
How to associate the XML document with the XSLT to
generate WML document.
Whether i have to use XSLT processor or XML processor
or both.I have no clue.Please do me this favour.
Laksh.

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