---PLEASE Read all BEFORE proceeding---
Do a search for *.dbx (both machine - note location on new)
These will be in your OE folder most likely (unless someone or something changed it)
The * will correspond to "inbox" , "sent", etc
Just copy all of these over & paste each one IN PLACE OF the ones on your new install.
NOTE: this will replace what you currently have as emails (& assumes the old is either empty or of no value)
If you have others to save then check out this link as I THINK it explains how to merge the two by importing.
http://discussions.virtualdr.com/showthread.php?t=194455
Basically - just rename the old INBOX.DBX to INBOX2.DBX & import. Then in OE just copy the emails to your other folder. Delete the one with the added "2" when done. - do this with all the DBX files. (some will [should] be empty - such as outbox)
BTW: saving these DBX files is how you can back up OE. (for anyone that is interested)