Your current Outlook data is already a PST file, you just
have to find where it is and copy it to another
computer. Search for *.pst and choose the one which has
a Date Modified that coincides with when you last closed
Outlook. When you move it to the new computer, if you
want it to become the default file, then find the
existing default file using Search (as above) and change
the name of the default file by at least one character
(or delete it if you don't want it); when you start
Outlook again it will tell you it cannot find the default
file and allow you to point it to your file, newly copied
from your old computer, which will then become the
default file always opened by Outlook.