Copy the *.pst file(s) to cd, from cd copy to new pc. Do NOT overwrite any
existing pst. Ensure read only flag is off, then start OL, File/Open/Data
File (depends on version, which you omitted) browse to pst and open it.
You then have the option to cut and paste to the pst you wish to
keep/update. Close the old pst, if required, and delete it if neccessary.
The pst is a hidden file.