Outlook 2007 on Vista OS

Had a mother board failure on my Acer computer. Have the hard drive now on a USB to my new computer. Did a search for my *.pst file for Outlook 2007 on a Vista OS looking for hidden files and directories/ system files and only get pst files that Acer had put out under program files. Can't find the pst file for my personal folder to import to Outlook 2007 on my new systeem. Anyone have a clue why I can't find it.