New Videocard for Mac Pro 3,1 - Xeon 3.2 GHz (X5482) Quad-core processors

Hi guys

Am hoping you can advise me.

Currently I have a

ATI Radeon HD 2600 XT with 256 MB of GDDR3 SDRAM (two dual-link DVI ports). It was the card that was already installed at the time of purchase.

I have not had any problems with it at all but as I do a lot of 3D (Cinema 4D) I think I would benefit from something more powerful.

Can anyone recommend a powerful card that would 100% be compatible with my mac spec please?

I have read an Nvidia Quadro FX 5600 is compatible. Does a Quadro 4800 for mac work also or any others?

I look forward to hearing your responses.

Thanks

Sophia