Here's a real challenge and one of the rare potential targets for MVPF if it follows the same principles as MLPF. MLPF 64bit did support the ATI X1600, so this one could have a chance of running Mavericks with the 64bit kexts.
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I don't believe that card was even supported in ML; you will probably find you need to replace that card by a more modern/more common card that is supported by ML and Mav.
Unless you can fiddle with the ATI/AMD kexts and patch them to support your card. You can always check if its PCI ids are covered by the current kexts.
RV-ABZ: Thank you for the advice, I appreciate it. I thought it would be so. I don't mind buying a 5770 (matter of fact, I had already planned that), I would just like to know if I can get it to run this way, until I either find a place where to pick a 5770 up or I get it shipped from Apple
As far as doing what you suggested, I am not that sound in that area, I would have to ask somebody who has any idea of what they're doing
I'll ask around, maybe a hackintosh site?