i have the same board with an Geforce 7300GT AGP card
i had to remove the NVidia Kexts by hand to succesfully boot into OSX

try the follow

boot at darwin boot prompt with command -s
and then do

/sbin/fsck -fy
/sbin/mount -uw /
rm -R /System/Library/Extensions/Ge*
rm -R /System/Library/Extensions/NVD*
rm -R /System/Library/Extensions/NVinject.kext
exit

after that ur macos should boot...

now i have the problem at the "Do You Already Own A Mac" loop :P
but i will fix that!

maybe there is an workaround for the NVidia Geforce 7300GT or older cards on AGP port
does any1 have any infos about that?

grtx ^fire^

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HomeHackintosh:
AMD Athlon64 X2 4400 :: ASRock ALiveNF5-eSATA2+ R3.0 :: Corsair 2GB DDR2-800 :: Gainward Geforce 8800GS PCI-E :: Maxtor 250GB SATA HD :: Audiotrak Maya 44 USB :: Phillips 22" 220AV TFT ::
Custom 10.5.5 Voodoo_Beta2 Kernel

Minimacbook:
Acer Aspire One A150X Netbook :: Intel Atom 1,6Ghz :: 1GB DDR2 :: Seagate 120GB SATA HD :: Acer 8,9" Crystal Bright TFT ::MSI Wind OSX 10.5.4 upgraded to 10.5.5 & Voodoo_Beta2 Kernel