In my case it was fine, not the same mb (MSI K9AGM2) but 10.4.9 needed legacy disabled in Bios. Installed the Zeph 10.5.2 R1, reactivated legacy again and it was all there.
Have a lot of issues however with 10.5 so I've gone back to !0.4. for the meantime.
Could you not reactivate Legacy in the Bios before you boot from the stick? Switch it back when rebooting to Osx?

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My Hackintosh:
Kalyway 10.5.2 Intel/Amd -- Speedstep, Netkas Smbios, AMD test patch 2.
Mobo: MSI K9AGM2
Chipset: AMD 690v ATISB600 -- SB600ATA kexts
CPU: 3Ghz AMD Athlon 64x2 6000+
Ram: 2gb Rambo DDRii 667
Graphics: Nvidea MSI nx8600GT 512MB -- NvInject 512 (fully supported 100% working)
Audio~External: Focusrite Saffire -- (100% working - ootb)
Ethernet: 8101E -- Realtek R1000 (100% working)
HDD: 320GB WD SataII (150gb Boot Partition)
150gb Lacie Firewire/USB RIP my dear Lacie.