Problems using live CD on new machine

[Richard]

I have a new AMD Phenom 2 x4 on an Asus 4GB M4A78 Pro board. The
chipset is AMD 780G / SB700.  I Googled this before buying the machine
and found statements that people had run linux satisfactorily with
it, and I understood that Asus was OK.

When I try to boot the machine from the 9.04 CD I get the main Ubuntu
menu OK, but when I try to run the CD live, I just get a black screen
with a blinking underscore cursor at the top.

I have tried the various options offered like safe graphics mode,
ACPI=off, noapic, nolapic, but they don't solve it.

Any suggestions as to what else I might try (e.g. BIOS settings).

The board has built-in graphics (ATI-based, I think).  Is it likely that
this might be a problem?  Might adding a pci graphics card be the
solution? Or might I need a proprietary driver?

One other peculiarity with my setup is that my HDs are running off a
pci disk controller, but that shouldn't stop the live CD from running,
should it?

Does anyone else have this M/B + processor hardware?

- Richard Kimber