I'm looking for a tool to simply try and read every sector of the hard drive in my iMac. In the PC world, I simply download the diagnostic tool from the hard drive manufacturer's website, burn it to a cd, boot it and let it run for a few hours. However, I've tried the diagnostic CD from Western Digital (the mfgr. for the HD in my iMac) AND the Hitachi diagnostic CD (known to work with any mfgr. hard drive) and neither will work. Both boot up into DOS, but because of the lack of a BIOS, the software won't run. Specifically, both applications make use of the "A20 gate" (address line) which isn't present on a mac. Any ideas? The diagnostic test on the Leopard install DVD seems woefully inadequate. It seems to do a few random seeks and thats it.