Quadro FX 3800

That's a good question but I think the answer would be no. I'm not sure it's up to system software in this case, it may be a physical thing the Mac hardware needs to have to start up.
But stay around, more opinions are coming.

No video in Mac OS so you'll be blind w/o another card at a minimum.

If I were buying a card today, I'd be drooling for ATI 5870 to come to roost, or for Windows pick up GTX 285 even - I may be wrong but prices have been fluxuating - and the cost of Apple's and PC for 285 are closer now due to price increases. And shortages. The GT300s aren't out yet either.

Don't scoff at gaming. Sometimes a good gaming card does a fine job with serious apps. In your case I'm wondering just how much an edge Nividia will give you over the Radeon 4870. The Radeons seem to be born to work great on these machines and for Apple apps they seem the best out there.

We live in a very imperfect world.

There is no "basic VGA" output the way you can with Windows when there is no driver installed yet, and in Safe Mode.

Some cards have even been known to block Mac OS from booting, though that seems rarer now than 3 yrs back.

An ATI card with 1-2GB would be nice, an Nvidia GTX comes in second.

There are no drivers (yet) for any ATI 5xxx series (just coming out and still pre-order status, won't hit mac if at all until the next model year).

Adobe and Nvidia came up with Quadro CX which is dedicated CUDA/GPGPU card optimized for 64-bit CS4 on Windows, more parallel processing than you can get now, and only $1499.

Video cards have to have EFI FIRMWARE to work. No EFI, no video out unless you can find someone that has developed special drivers, injector, that loads support after the kernel loads, but those are for PC versions of existing Mac graphic cards.

It's not good to tell rumors without the source to back you up, but I could have sworn I read that in all this time, Nvidia has not come up with a single card that targets Apple's own apps.
And my personally made up rumor is that when Apple designs it's computers, most of the time they already have a Radeon installed. They seem that synergistic.
My continuing tirade: Boycott Nvidia until they consider Macs more than an afterthought.

The GT120 and FX ought to work, or very good chance.

Aha, both Nvidia. One-one slot, one- two.

Edit: Have to wonder though... a top notch card with a mid level machine. Seems more benefit in getting an 8 core.

Message was edited by: Samsara

That's cool, you obviously know your way around. Your choice is a good one then in my opinion. 🙂
Good luck with the new machine and your new cards!

Message was edited by: Samsara