It makes very little difference (if any) which software you use.
This one
http://www.microsoft.com/downloads/detai...
Microsoft offers a free plug-in for Office programs to convert to PDF format.
Pdf995, PrimoPDF, CutePDF or SourceForge PDFCreator are free alternatives to Adobe Acrobat which will allow you to save your document to PDF format. Once one of these are installed you can simply "print" from your document to PDF.
If you don't want to download software you can convert your document online for free at pdfonline.com