ProRes422 effects rendering and graphics card

Question

We are having problems with effects rendering and playing using Prorez 422 HQ.
Our system is: Mac Pro 2x 2.66 GHz dual core Xeon, 4GB RAM, with a NVidea GeForce 7300GT graphics card with 256 MB VRAM, pulling media off of a Facillis Terrablock.
We get the following error message:
"The effect "Desaturate" cannot be rendered in sequence of this size with the current graphics card"
The time line shows the effect as rendered, but it will not play in the canvas desaturated. It does show in the Browser desaturated.
Settings are at Safe RT, High Quality, full frame rate - we need to go out to tape.
Obviously, the error indicates we should use a different graphics card, but is this correct? Everything else I read indicates that this card should be enough to edit and do effects with in FCP. Is there a problem with using this card for Prorez or HD material? Is there a settings issue we should be looking at? What is the recommended card? Are there any links to the recommendations or known issues? Any help is greatly appreciated.
Thank you,

Answer 1

I'm assuming that's an FXPlug filter. ATI cards handle FXPlug filters netter than nVidia cards, so if that's the problem, I wonder if one of these workarounds might help:
1) Place the clip, with enough heads and tails to allow for transitions in the final sequence, in a new sequence, apply the filer and see if it renders OK. Export that to a QT movie, import that back into the project and drop it into the final sequence in place of the unrenderable clip that's there now.
2) Put the clip into a new sequence, apply the filter but don't render. Export to a QT reference movie, and drop that into Compressor, and select the same codec as you are using for the final sequence and see it that will render.