I picked up a couple of imac(400 with 128 ram) and they didn't come with an OS installed. I tried to install the newest version and an error said that it could not find the driver and I have to restart. I wanted to take out the 10.4 disk and find an older version ti install but I can't eject the disk. How do I eject the disk and what OS is best for this system(9.?)?