IF the workstation is purly for rednering and working with 3D and compositing etc... I would say get the FireGL, but you want to use it for leisure, so get the NVidia Card.

FireGL as really poor at supporting gaming, but the NVidia cards are great at dealing with 3D software and compositing. I have read in 3D World tht some studios are dropping the expensive Hardware rendering cards like FireGL in favour of the cheaper 7 series cards from NVidia as they are just as good at dealing with rendering as the FireGL's.