Q: what would be better? NVIDIA GeForce 8600M GT with 512MB, or Radeon 9250
A: 8600 GT by far. Seeing that you have a laptop, everything will run at lower resolutions, meaning that the card will push out more Frames per Second. You could run DX10 games pretty decently, I imagine. I would wait, though. Newer series are coming out with the superior 9M series cards.