I have the same problem with 10.5.2. What I have to do? Although 10.5.1 installed fine
My specs:
Processor: AMD Athlon™ 64 X2 5600+
Motherboard: Asus M2N32 SLI Delux WiFi edition (chipset nForce 590 SLI)
Graphics: NVidia 8600 GT
Hard Drive: Seagate 320Gb SATA, Seagate 80Gb IDE (for MacOSX)
DVD-RW: Optiarc DVD RW AD-7173S SATA
Sound card: SoundMax ADI 1988B
Memory: 1024 x 4 DDR2 OCZ PC7200

Can I modify ISO with some Windows utility to insert/delete necessary kexts?

Here is the screen: