Are you asking about the auto-fill feature in outlook? And what do you mean by outlook 6? outlook xp is outlook 10, outlook 2003 is outlook 11 and outlook 2007 is outlook 12. What is 6?
The autofill or autocomplete feature is configured as you go along in outlook. A file by the name of .nk2 is a growing, building file. When you enter an email address the next time you start typing their name in the to field the name should autocomplete itself provided you are using outlook 2003 or 2007. If you change computers or reformat your drive and reinstall outlook this file will be empty and start building itself again from scratch as you send emails out.