Well, after hours on the phone to AppleCare, it seems the issue was the mini-displayport to displayport cable. Having this plugged in at the time the machine was turned on completely disabled the graphics card to the point where it would no longer show up in the system information dialogue. It seems there are cables on the market which aren’t properly made to spec and this was causing the issue. This was NOT identified by AppleCare, and they didn’t seem aware of the possible issue.
I purchased a mini-displayport to female displayport adpater, then connnected the Dell 27″ via the cable it came with and everything now works as it should. This tip was suggest in the NEC tech-note.
The adaptor is a product from monoprice. This company is selling the adaptor in Australia which is a cheaper way to get the same thing and avoid expensive shipping. (The monoprice logo is gone in the photo on the product page, but it IS the same thing).
I find it a little strange AppleCare never even suggested this could be an issue. Obviously the setup is not exactly common, but I know there are plenty of design and video houses using mac pros with non Apple screens in multiple monitor setups. Hopefully this post gives anyone experiencing the same difficulties I had a quick (and relatively cheap) solution. It would be great if Apple would release an adaptor as well. They have mini-displayport to DVI, VGA etc, why not mini to full size?