Solved it, more or less.

The trick is to use exactly the right BIOS settings and
then Mandriva 2008.0 (the 32 bit version) works fine,
including seeing both processors and the SATA devices.

Here are the BIOS steps I used to get it to work properly, the important
ones are preceded by [#] with comments below:

load optimized defaults
[1] HPET support: enabled -> disabled
[2] ATI SATA type: Native IDE -> AHCI
[3] ACPI xsdt: LEAVE at disabled (enable for 64 bit OS only)
DRAM timing mode: auto -> maxmemclk (to enable the next change)
memory clock: ddr2 400 -> ddr2 800 (run the memory at full speed)
spread spectrum: enabled -> disabled ( this likely does not matter)
boot order: CD, Disk, Nothing (system has no floppy)
full screen logo: enabled ->disabled (else it hides the BIOS text)
fdc controller: enabled -> disabled (system has no floppy)
init display first: pci slot -> onboard (onboard is only display)

Notes:

[1] If HPET is enabled the boot will always stop at
NET: registered protocol family 2.
Now why it stops there is an interesting question, but
one I cannot answer at this time. In any case, it is
possible to get past that with "acpi=off irqpoll"
or "acpi=off irqfixup". Sadly, while it runs,
only one processor comes up. If "acpi=off irqfixup" is
used then the setting of HPET is apparently ignored (nothing
seems to change), so changing HPET in the BIOS with those
boot settings is not informative.

[2] The default Native IDE setting is sufficient to install
on a SATA disk if the installer is run with "text, acpi=off".
However, during boot from the SATA disk all hell breaks loose
during the udev part. When running from an IDE disk with other SATA
devices in the system instead udev hangs for three long minutes
before boot completes, and then the SATA devices are not visible.
Change this to AHCI and everything just works as it should.
I believe, but have not confirmed, that with this set to "AHCI"
in the BIOS the installer should run so long as "text" is used,
with no acpi switches required.

[3] I have only tested 32 bit Mandriva 2008. For the 64 bit version
this should probably be enabled.

I also tried upgrading the BIOS from 690g10m to 6gm210m (from a
temporarily installed floppy drive), and running the very
latest kernel, 2.6.24.2. Neither of those changes eliminated
the need for HPET to be disabled. The affect of these changes
on the ATI SATA type behavior has not yet been tested (the hour
was late and I was tired of rebooting).

Once the BIOS was set as above and Mandriva 2008.0 running normally,
mcc was able to correctly configure the display. The installer was
not able to do so during the initial install, which was run with
"text, acpi=off" and the ATI SATA type as "Native Ide". I do not
know if the installer would have been able to configure the
display if the BIOS settings had been right at that time.

Regards,

David Mathog