your system is lacking a decent videocard... still it should run better than this, I would do some better entity handling, such as deleting entities that arent going to be used. Its going to be hard, but one thing to remember is that is better to have one big model than many small ones. With a machine like that, your going to have to do a lot of tweaking to get it to work but it is possible. You'll never get great graphics, but you should be able to at least achieve some stuff like gta III graphics.