It's important to know which version of Outlook you have on the old computer, and what version of Outlook you have on the new computer. If it is Outlook 2000, Outlook XP, or Outlook 2003
go here: http://support.microsoft.com/kb/287070
Keep in mind that the .pst file is what holds all of your mailboxes, e-mails, and contacts (assuming you use Outlook to manage contacts). It does not contain information about that actuall e-mail account. In other words, you will still have to enter incoming/outgoing mail server information for your account in Outlook on the new computer.
For help with configuring Outlook to access your E-mail account on the new computer
go here: http://office.microsoft.com/en-us/outlook/CH063565691033.aspx
Hope this helps!