If you want to use Microsoft Word templates in OpenOffice, you can just open the template file (via File -> Open) and use the template. But if you want the templates to show up as options when you create new files in OpenOffice (via File -> New), you need to first convert the Microsoft Word templates into the OpenOffice format. This is pretty easy to do.

1 - In OpenOffice go to File -> Wizards -> Document Converter. In the first step, check the box to indicate that you want to convert Word documents. In the second step, file in the information in the Templates section to convert a directory (and possibly subdirectories) of Word templates into OpenOffice templates.

2 - Once the conversion is complete, you need to tell OpenOffice where to find the newly converted templates. Go to Tools -> Options -> OpenOffice.org -> Paths and select the Templates row on the Row. Push the Edit... button and then select Add. You'll get a file dialog, select the directory where you put the converted Word templates then push OK until you get out of the workflow.

You'll now be able to use all of your Microsoft Word templates in OpenOffice when creating new documents or templates.