Okay, after discovering that I'd probably never be able to get a flawless run out of the other motherboard I had, and not being able to boot OSX off of the IDE drive anyway, I got my Plan A motherboard running (turns out I had plugged the CPU fan into the system fan jack -- oops) which I had researched the hell out of prior to buying to make sure that it should definitely probably work.

What I get, as soon as the boot begins, regardless of what release I use (I've tried JaS 10.4.7, 10.4.8, and Uphuck 10.4.9 v1.3), after the copyright message from the regents of the University of California, the lines:

using 98e0 buffer headers and 4096 cluster IO buffer headers
Enabling XNM register save/restore and SSE/SSE2 opcodes
Started CPU 01
IOAPIC: Version 0x21 Vectors 0:23
panic(cpu 0 caller 0x0019DACB): copy_window_init: cpu > num_cpus
Debugger called: <panic>
Backtrace, Format 0 Frame : Return Address (4 potential args on stack)
0x2298bca8 : 0x128d1f (0x3c9728 0x2298bccc 0x131ed0 0x0)

...and so forth like that last line, until:

Backtrace terminated - invalid frame pointer 0x0
Kernel loadable modules in backtrace (with dependencies):
com.apple.driver.AppleACPIPlatform(1.0.3)@0x32cb90 00
dependency: com.apple.iokit.IOPCIFamily(2.1)@ox32c6b000
dependency: com.apple.iokit.IOACPIFamily(1.2.0)@0x32c7e000

Kernel version:
Darwin Kernel Version 8.8.1: Sat Dec 9 22:17:27 AZOT 2006; semthex:/nebukadnezar/BUILD/obj/RELEASE_I386

My system is as follows:
Motherboard: MSI K9AGM, which says it is ATI RS485/RS485c chipset based
500 gig SATA hard drive
320 gig IDE hard drive (there's a failed install on there from the other motherboard, but this problem happens even when this drive is unplugged)
AMD Athlon 62 x2 4800+ dual-core processor (doesn't like my dual-core maybe?)
2 gig stick DDR800 RAM
And a DVD-RW drive I picked up for cheap.

I'm at wit's end here. I've been trying to get this thing up and running for a week. Any help would be greatly appreciated.