Synchronizing/importing/sharing Outlook and outlook express

I've Outlook 2003 on my work laptop which I use for work/business related emails.  I had also been using it to add/synchronizing my contacts/calenders/tasks etc from my PDA.  These included all personal and business contacts/tasks/calenders etc.  I now want to manage all my contacts/calenders/tasks in outlook express 6 which also installed on same work laptop.  I configured outlook express to work with gmail and want to maintain synchronization between outlook express 6 and outlook 2003 and my PDA.  I understand that I'd probably do sync between PDA and only one of the email clients and then can sync the other email client later.

How do I do this?  To sync data between outlook express 6 and outlook 2003?

Thanks.