Assuming you have access to Distiller, the best way to make a PDF from a Word document is to do the following steps:
1. From the Print menu, choose Distiller as your postscript printer, and check the 'print to file' box. Ensure you save the file somewhere you can easily find it again. The process will generate a postscript file, which from Word, will probably have the extension PRN.
2. Launch Distiller, and use File>Open to open the postscript file you have generated. You may need to choose 'all files' from the File Type box, as the default is to only see files with the PS extension. But once you have found the postscript (PRN) file, you should be OK.
3. Select the appropriate job options from Distiller's settings, or as Travis suggested, ask the printers what settings they want you to use. The highest quality PDF has the least compression (and depending on what version of Distiller you have) will be found under the PRESS setting. Once you have selected this (or the printers job options)setting, you can click OK to make the PDF.