I just bought my first Mac, a used mac pro, the 2 x 2.66 Dual Core Xeon version. It is currently running OS X 10.5.6. I would like to wipe the hard drive clean and reinstall OS X. I understand this would get rid of unwanted software, let me change the administrator, and let me set things up how I want. I tried booting up from the install disc, by starting the computer while holding down the "C" button. It said I can't install the install disk's version of OS X because a newer version is running on the computer. My question I guess is pretty simple: How do you erase a Mac Pro and reinstall the OS? I've also heard that its better to "zero out" a used hard drive, which will help it will run faster. Should I do this and how? The computer may also have applecare warranty left on it, should I get this transferred before reinstall the new OS is this not a concern? Thanks.