Definately a good idea. I installed OS4 on my A1200 today and slected my graphics card as Voodoo PCI. However I cannot access this card and under show cofig no pci cards are listed. There is however an entry for the mediator board so I'm a bit stuck.
In answer to your question hard rive capacity should not be an issue.I've got 256MB RAM installed and even running on AGA the system is fast. I hope this graphics problem can be resolved.