9500GT is a weak graphics card.
I assume when you say Ram 4gb @ 3.18 you mean 3.18Gb are read by windows, not the voltages :O
I would get a better GFX card. A GTS250 or a Radeon 4870 or even a Radeon 5770 or Radeon 5750. Anything really! 9500GT is lacking in stream processors, and overall grunt.