Well you will all be pleased to hear that I have a new system now. Built a Haswell i3 @3.4ghz with 8gb ram. very similar to the suggestion a few pages back. Using some new and some used parts. Total cost £183. Waiting on some gift vouchers from work for a well known PC chain in the UK to buy a graphics card. So using the onboard graphics for now and with 0.6K all I can say is......
Holy FPS Batman!!!!
Can race a full field of AI, sky on, rubber in, car reflection things on 8, AA on 4x and never drop below 60fps running at 720p.
It's a completely different experience. Amazed!!