Most of PDF converter   are not free ,but there are few services which will do this for free with some limitations.I’m  listing  Top 4 freewares among them.

1. PrimoPDF

This free tool has  features like security, document merging after conversion and can create PDF files  from more than 300 file formats.Created PDF files can conform to the Industry  PDF 1.4 & 1.5  specifications. Compatiable with all Windows OS versions,including vista (64 bit).

Download link: http://download.cnet.com/PrimoPDF/3000-10743_4-10264577.html

2. PDFCreator.
PDFCreator is a free tool to create PDF files from nearly any Windows application and has all most all commerical features.

Download link: http://www.pdfforge.org/products/pdfcreator/download

3. doPDF
doPDF is a free PDF converter for both personal and commercial use. Using doPDF you can create PDF files by selecting the “Print” command from virtually any application. With one click you can convert your Microsoft Excel, Word or PowerPoint documents or your emails and favorite web sites to PDF files.

Download link: http://www.software112.com/products/dopdf-free-pdf-converter+quick-download.html

4. PDF4free

This  is  a free solution for creating PDF files from any Windows application. More precisely, it allows users to convert almost any kind of electronic document into PDF format.

Technically, PDF4free is a bundle of several software packages, coming from different sources:

* SavePDF, that is the user interface for the whole thing.
* RedMon, by GhostGum, that monitors a “virtual” port for printers and redirects the printouts to SavePDF.
* GhostScript, by Aladdin/AFPL Software, that does the actual conversion in PDF.
* The NSIS installer engine.
* Some other small utility programs (UpdSpl, AskReeb), necessary for the correct installation and configuration of the package.

Installation and basic configuration for all of these pieces of software is performed automatically by PDF4free installer, so you shouldn’t concern about any detail if you are not interested.

Download link: http://www.gicomsrl.it/pdf4free/pdf4free.exe