id go with a gt240, its faster than a gt430 and probably cheaper, it doesnt have dx11 accelleration, but the gt430 is so slow it would grind to a halt if you enabled dx11 in any game that supports it. You have to realise that any game newer than 2003 will probably struggle on a single core P4 cpu regardles of your graphics card. If your motherboard supports socket 775, then you may be able to upgrade to a dual core p4 or core 2 duo.