Hello,

What for bootloader do you use?
I would try to start with flags -v -x arch=i386 cpus=1 busratio=xx (xx=your busratio)
(often the flag cpus=1 helps; if it is you can fix it by edting the dsdt)

If you know what for bootflags are needed you can insert them into boot.plist.

What for kexts have you checked at the installation?
Which version of leopard have you installed and which voodoo kernel do you use exactly?
What for a graphics card do you have?

But i would setup snow leopard because you can run 64 bit with it.

Greetz