Poor quality PNG image when printing to PDF in Word 2010

The PNG format is not suitable for what you are trying to acheive.

You mention that you have an EPS version of the logo.

I would insert the EPS directly into the Word file for the best results. The EPS file is a vector graphic format that will allow you to resize it without getting the scaling artifacts you get with bitmap formats.

The only issue with doing it this way is that Word will display and most likely print a bitmap preview image instead of the actual vector information. But, when you print the Word file to PDF the vector information will be embedded in the PDF.

Instead of Printing to pdf (file > print > select Adobe pdf), publish to pdf (file > Publish as PDF or XPS). When you select Publish the dialog box opens, the drop down menu says PDF and if you look down, grayed out it says high quality printing. You can click change to adjust the settings, but if it's set to high quality printing you may find that you don't have to. Crops and bleeds options can also be found in the print options when you hit Change.