Are Realtime HD Previews Possible With An NVIDIA QuadroFX 5600?

Hello AE experts!

I have a Panasonic HVX-200 and I record HD using their P2 format. Currently, I use an excellent utility on the PC called Raylight from DVFILM. This allows me to convert files from the Panasonic MXF format to an AVI file that After Effects CS3 can then obviously work with.

My question is what kind of an Open GL card do I need to be able to do a 100% full quality real-time preview of at least two HD streams mixed together? (I hope all of you aren't choking on your lunch at this point!). These HD streams are of course compressed, with data rates of 100 megabits per second each, so virtually any hard drive would be able to keep up with supplying the data in a continuous uninterrupted stream.

I am about to buy either a MAC or PC based Dual Quad Core Xeon system but would like to know if a high-end QuadroFX 5600 would be able to generate the real-time previews I mentioned above. Even using just the Dual Quad Cores I would highly doubt I could approach real-time rendering so I was wondering if this is actually possible with high end workstation video cards.

OR, can this even be done with something less expensive than this card? I can find very little information on just what kind of actual real-world performance I can expect from such cards (or at least combined with AE), and I obviously don't want to spend more than I have to. However, at this point I don't know if this is all a pipe dream or whether such an NVIDIA card would just laugh at what I am proposing to throw at it.

Do any of you out there have direct experience with doing Open GL previews with the higher end cards while mixing multiple layers of video (and preferably video that is of a higher bit rate and quality than regular DV)?

Thanks!

Brendan