transferring mail data from one PC to another one

I want to setup a new Vista on my second PC (not an image backup, but with
same user name) and to move *all* my mails from PC1 to PC2. The old PC1 has
a lot of folders and subfolders. Simply copying mail folders does not work.

Therefore I tried a transfer by Files - Export with target Microsoft
Windows Mail which should export mails directly into another Windows mail
sytsem. It first looked fine while running but after completion I found that
about half of the folders dont't have been exported. There was no error
message.

Can anyone tell me what can be fine tuned to copy all folders and mails, or
is there a mail backup application out there which does not only export
mails and folders into an external database but also allow *reimport* of
these exported folders into an existing Vista Mail database? All mail backup
software I found did, if at all, only support folder export but none did
allow folder import.

Or has someone another idea to move the mails to the new PC2?