I had some great help last night regarding the need to get a "Black" retail disk in order to install Tiger onto my iMac, I have searched on ebay and have found some grey disks which read - "For Mac Computers" on the left hand side. In small print at the bottom they have 'Mac OS version 10.4.10, AHT version 3a133, disc version 1.0, 2z691-6089-A' The guy selling them said he had them from when he brought his MacBook !!! - Which is the worrying bit - Will they install on a White Chunky G5 Power PC iMac? Thanks in advance