Hi, my iMac has Leopard OS 10.5.8 installed, when I try to upgrade the OS to Snow Leopard OS 10.6.3 and put the installation disc in it's super noisy but sounds like it's trying to read the disc and after a while the iMac just ejects the disc. Restart doesn't help, or unplugging the power source. Apple Support couldn't help when I called them. It should be possible to install Snow Leopard on the iMac, but not the later OS like Lion etc. iMac specs are: 17" early 2006 model, 1.83 GHz Intel Core Duo, 2 GB memory, OS 10.5.8 I tried other DVDs, a movie DVD loaded without problems and started playing but a game installation disc (Sims 3) had the same problems as the Snow Leopard disc. I just got the iMac back from repairs where a new hard drive was installed. The iMac used to have Tiger on it, and the repairs company installed Leopard on it. The DVD drive isn't super important for me, I only need it for this Snow Leopard installation. Thank you in advance to anyone who can help me!