Hi Clarke,

In versions of Word through 2002, you have to insert a section break
before and after each table. Then go to the Tools > Protect Document
dialog, click Forms, click the Sections button, and uncheck the
sections that should be editable.

In Word 2003 there's a new feature on the Protection task pane, where
you select parts of the document (no section breaks needed) and
designate who can edit them.

--
Regards,
Jay Freedman
Microsoft Word MVP        FAQ: http://www.mvps.org/word