Okay. From what I recall, I think that the backup/restore of courses is what was suggested somewhere up above.
Try to backup one of your old courses in your old Moodle, and I think that you want to include "users" from that course from what I recall. Download this file to your local computer when Moodle is done with the backup. Then, go to your new installation and restore your old course file. The restore, which involves moving your backup into a dialog box which "uploads" the old course, could take a while depending on your server speed.
I forget how many courses you have. But doing this for one course will let you see if you have success.