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OP If you aren't who the others think you are, then what you need to do is use disk utility to burn a copy of the Windows Vista ISO to a DVD. That's the only thing you will be able to do to help fix this using the G5.

With that done, go to your PC, stick the freshly made DVD into the drive on the PC, and select boot from CD/DVD from the BIOS.

It should boot and allow you to install Vista.

Make sure you install any updates and service packs immediately then install AV. After that you can install your applications.

And that's it.
 
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