GeForce 8600 GT 512MB works just fine, as I have used one in my hackintosh,

BUT, I was using a Desktop PC, with a PCI Express Video Card, and had a
vanilla install from the retail DVD

So there are two things to think about,

(1) Could it be that because its a Laptop IGP and not a regular video card
(2) Could it be the Distro you are using,

Have you tried EFI Studio?