Hi...

I need a batch script to convert a PDF file to a text file on window xp.Any idea ?please help me...

PDFs and text within. Have you ever viewed the coding of sample pdfs? The text content is in binary. PDFs with text can also in fact be images of documents. My advice would be to invoke a pdf reader such as Foxit, and the text view within, select all and to copy. Batch that. Of course that won't work with document images.
Else use something like PDF Text Extractor; there are also command-line versions.