So you’re after better viewport performance?
Then the Quadro600 is/was a waste of money to begin with.
Blender does not benefit from the Quadro features, and on top of that it’s even crappy compared to other quadros and quite expensive.
GPU Passmark Scores:
Quadro 600, 170 USD, Score: 685
Quadro 6000, 3700 USD, Score: 3411
If you want a fast viewport, depending on if you need CUDA or not either get:
For fast viewport and fast CUDA usage to render: GTX 580 3GB.
For fast viewport and possible fast future CUDA: GTX 680.
For fast viewport: Radeon HD7950 or better HD7970.
To show up the relations, a GTX680 would be the fastest single GPU card currently available.
Compared to your Quadro 600 it costs 2.7 times more, and is 8 times faster.
And if you have high poly models, you need lots of memory, also be sure to have an OpenMP Blender build.