You can download these free/opensource software for your windows installation to create pdf files.
They all work almost the same. After downloading the software, they will create a virtual printer on your pc. All you have to do is just print the document from Internet Explorer, Notepad, Microsoft Word, Openoffice.etc anything you want really. When you print, normally a message box will pop up asking you to save as. This will be the pdf document. Personally i prefer the first 2 (dopdf or pdfcreator) they do not place any watermarks on the document you print. Happy printing