Installaing cuda with cmake-gui

Hello and thanks for this forum.
I am in windows Vista (using Qt + opencv).

I try to install CUDA 5.5.

My NVIDIA is the Quadro FX3800.

I’ve installed de sdk but when i set WITH_CUDA to ON in the cmake-gui nothing happends.
I have :
Other third-party libraries:
Use IPP: NO
Use Eigen: NO
Use TBB: NO
Use OpenMP: NO
Use GCD NO
Use Concurrency NO
Use C=: NO
Use Cuda: NO
Use OpenCL: YES

Cmake do not let me specify the path to cuda sdk or something.
I don’t know how to install cuda.

Could any body help me?
Thanks a lot and sorry for my bad english (from Paris)