Outlook
Migrating Outlook 2010 autocomplete file from one computer to another.

Comparing to Outlook 2007 there is no such thing like nk2 file in Outlook 2010.
The equivalent file called "Stream_Autocomplete*.dat" and located under

"C:\Users\%username%\AppData\Local\Microsoft\Outlook\Roamcache"

So if you want to migrate or transfer autocomplete settings to another computer just copy the above file over and name it as per similar file on the target computer.