These are primarily in .acl files, but formatted entries are stored in normal.dotm.
See "How can I import and export all my AutoCorrect entries, so they can be transferred to another machine?” at:
http://word.mvps.org/FAQs/Customizat...utocorrect.htm. See also AutoCorrect2007.zip The AutoCorrect backup/restore template updated for use with Word 2007 and Word 2010.