Is it new?
If it goes wrong at the very beginning, my usual recommendation is to insert the installer DVD, boot to that, and do an erase and install. The complete install from the disk does not ask for disk 2 on new Macs, so when you get to your desktop after the system setup, insert the disk 2, and follow the instructions to install the rest of your included software.
Come back here if that doesn't work (or even if it does - good news is appreciated, eh?)