Word Options > Proofing > Grammar & Style Settings > Spaces Required between
sentences.
Not quite, but close enough that I found it. Thanks.
In Word 2007, it's
* Word Options
* Proofing
* When correcting spelling and grammar in Word
* Writing style:
* Settings
* Spaces required between sentences
Curiously, this is one of several settings that is maintained twice,
once when Writing style is set to "Grammar Only" and once when it is
set to "Grammar & Style". If you switch between the two Writing style
settings, you need to set the Spaces required setting twice.
I think Word's proliferation of options has exceeded the capacity of
the programmers to control.