PDF files are mostly made to be viewed and not edited. Your use of the word "open" may imply that you want to edit it. Editing a PDF would only be possibly if they allowed such. Most PDF authors just want you to view the content with Acrobat Reader.
Acrobat Reader for Windows ME is over at http://www.adobe.com/products/acrobat/readstep2.html
Hi, can someone tell me how to open a pdf file please.