The PPro specifications do not show that card http://www.adobe.com/products/premiere/tech-specs.html
http://www.geforce.com/hardware/notebook-gpus/geforce-9600m-gt/specifications does not mention video memory... so my GUESS is the card does not have enough to activate CUDA support in PPro
I think cards need 1Gig of video memory to work with hardware MPE in PPro
My card has vram 512 mb.
Your card supports CUDA, but you do not have enough VRAM. Premiere needs at least 765mb, but you have 512mb. As of my knowledge one video track uses 200mb of VRAM using CUDA. So, I do not understand why it uses 765mb limit.
I tried to enable CUDA on 9600M 512mb using
and it did not work for me.
You can try to replace your video card to make it work. I am searching a card for my laptop right now.