Ok ok folks I got it on there by golly (and after I felt really silly for not thinking of it sooner)
Step 1: Put the old hard drive into the old 360 and uninstall FFXI.
Step. 2: Put the old hard drive into the new 360 and install FFXI.
Step 3: Put the new hard drive into the new 360 and play. :o
Of course this all depends on whether your old 360 is still up and running, if it's not you'll have to try to buy a used copy and try installing it. I am lucky I didn't burn mine out.
So thank you thank you thank you for helping me guys.