Well i see that your CPU is quite weak but that should not be much of a problem, you might have some hiccups while using something controlled by Havok (the physics engine if you didn't know that) that happens to me and i have a 1.8 ghz dual core who is stronger than yours but still considered weak.
Anyway in your Steam right click on HL2 and choose properties, then you should see a button who reads: "Set launch options..." click that and a text box should appear. Copy paste this: -dxlevel 70 -high -d3d -nojoy -dxlevel 70 makes the game play in Directx 7, but here u can put -dxlevel 80 (for Directx 8) -dxlevel 81 (for Directx 8.1) -dxlevel 90 (for the deafult Directx 9) and also -dxlevel 95 (for Directx 9c). So pretty much choose anyone of these but as i told you before i recommend Directx 7. -high simply puts your game to a high priority, this can boost you a bit. -d3d is simply something i have experimented with, it supposedly will force the game to use Direct3D instead of OpenGL, and as MAD_BEAST and some others told me before, Intel's chips don't really like OpenGL, though i have seen it is better than Direct3D in the HL1 engine. But -d3d you can use if you want, i haven't noticed much difference but i have kept it there in case. -nojoy doesn't mean it will take away all the fun in the game :P But rather tells the game not to search for a plugged in Joystick, this will boost startup time of the game and might give some boot in game but don't count on it.But if you are using a Joystick while playing don't use that command. Thats all off game settings you can use that i can think of. But please give me a screenshot or something with your in game settings if you haven't put all to low or just want a little tweak. -- INTEL 9xx SOLDIERS SANS FRONTIERS
