@CDE_MusiX:
To make things easy to begin with, just get a 2.5" laptop harddrive and install the Workbench that came with your computer.
With that Workbench (3.0 or 3.1) practically everything works and it also needs much less resources (3.9 needs more than the A1200s stock 2MB chipmem to be really usable).
Also if you plan to attach an external CD-rom you will also need to get a beefier powersupply.
/Patrik
