Here's what works for me. It's a lot of steps but I don't know any other way.
From within OL:
File>Import and Export>Export to a file>Next>Personal file folder (.pst)>Next>
Highlight the folders you want to move. Check the “subfolders” box too.
Browse to a file you created that is outside of OL – say on your desktop and give a file name. (I made a folder called “email backups” on my C drive and use the date I create the file as this is how I backup my OL too.)
Highlight any of the buttons for replacing duplicates and >Finish>Compressible encryption>OK.
Copy this file to a CD or stick. Now go to the other computer. You'll do essentially the reverse of what you just accomplished.
Open OL and File>Import and Export> Import from another file or program>Personal Folder (.pst)>Next. Browse to the folder you copied (you may have to click “All Files *.*” to see it). Double click the .pst file that you created. Allow duplicates>Next>select the folder and where you want to put in, check subfolders > finish.
You should now have the entire OL folder structure and all files copied to the new computer.
Do the same with Contacts, Tasks and Calendar if these are required too.
BTW: The CD is now a backup of OL as it existed the day you made it. So keep it safe.