noapic nolapic acpi=off pci=noacpi irqpoll pnpbios=off vga=0x317
Gets me just past loading the kernel: something flashes up (first word is "loading", the rest might be "please wait") and then I hit a black screen with a static underscore.
My system didn't like switching native IDE to RAID either. It skipped the Heron CD altogether, tried booting XP and restarted itself every time the loading bar appeared.
If I get time I might try installing an even older Ubuntu disk and then upgrade it to 8.04.