Well, I seem to have found a solution...kind of.
It seems the i7 960 is a no go for device passthrough. I had a 950 lying around and threw that into the system, and at first it gave a pink screen of death as well...argh! but then, I remembered, for any VMs that have physical PCI passthrough devices, should have their memory "reserved", in the VM settings. Once I did that (with the 950), the VM with the Ceton passed through booted. It is installing Windows 7 as we speak, so we'll see if Windows can see the Ceton card properly.
In summation, i7 960 no good for device passthrough, but a 950 works fine. This is on an Intel DX58SO which does have VT-d support.