eelhead,
I looked at the Intel mini-ITX motherboard with interest. It is DH61AD, a low profile card that accepts 2nd gen Intel iCore CPUs and has two onboard mini-PCI-E slots, accepts DDR3 SO DIMMs AND has onboard DC to DC PSU where the input is 19VDC.
My knee jerk reaction was to go price out a system and check the CPU table. It appears that the ideal CPU for this card would be an i3-2125 (street price US $ 130), The MB is available from Amazon for about US $100. 8GB SO DIMM 1333 MHz for $ 30.
This thing should be able to run OS X Lion and HD3000 (with the CPU identified). However I have not found anyone actually admitting to have this combination running.
With my experience trying to get a PICO PSU to fit into a G4 Cube and space for the Proximity Switch board and harness, this card would be a breeze.
I have my mind set to try again with the Zotac H67IXT-C-E before giving up. If I were stating fresh, the Intel DH61AG motherboard would be my current choice. I did see that some expect Gigabyte to produce a version of the Intel design (just no date).
neil