If you and all the 'others' have Word 2003 or later, then you can protect
the entire document against changes and then mark specific areas as "editing
allowed" (that is, mark everything except the cells that you want to remain
protected).

If someone opens this document in a version of Word earlier than 2003, the
entire document will be locked, because the earlier versions don't support
partial unlocking.

You might also look at forms protection and using form fields where editing
is allowed (http://www.computorcompanion.com/LPMArticle.asp?ID=22), but
that's much more restrictive. Certain features don't work in protected
forms.

If everyone has Word 2007, you can insert content controls in certain cells
to lock their contents. These are not available in any earlier version.