automatic body text numbering in template problem

I am trying to create a template (Word 2003) where body text paragraphs are automatically numbered. This is easy enough to do by applying numbering to the Body Text style, but what I need is to somehow include the Level 1 heading number in the paragraph number, and also restart the paragraph numbering when a new Level 1 heading comes along. The final appearance would be something like this :

1 The first level 1 heading
1.1 A level 2 heading
1.1.1 A level 3 heading
1.1 Body text paragraph 1
1.2 Body text paragraph 2
1.3 Body text paragraph 3
etc
etc
....
2 The second level 1 heading
2.1 A level 2 heading
2.1.1 A level 3 heading
2.1 Body text paragraph 1
2.2 Body text paragraph 2
2.3 Body text paragraph 3
etc
etc...

If this is possible in Word I would appreciate some guidance on how to do it.
Thanks
jrm