Outlook too slow on a laptop

[yaip]

I have had MS Outlook on a desktop for a while and it has been running fine. I recently bought a laptop and installed MS Office Pro 2003 on it. I copied my PST file from my dt and copied it on my lt. Now when I try to open an email or just switch between emails to view the mail in the preview pane, it is extremely slow. What do I need to do to speed it up? I know it can't be the RAM as I have 2 GB on my new lt.