How to make world at war work on this.

as you already know from your own digging, its not going to happen until you upgrade that processor.

You're not going to be able to run games with that CPU. It's not worth spending the money on upgrading that computer trash it and get a new computer or build your own.

I don't want to spend money on a new one I just want to get the best out of what I have

Well you're not going to be able to. The processor is to old and can't handle modern games. You either have to upgrade the processor (which I wouldn't waste my time doing) or get a new computer.

ok

SSE is not the problem, the problem is that you are trying to run a multicore support title on a single core processor that is really old and tired now.

As the saying goes, you can't squeeze blood from a rock.

You can build a Phenom II x 4 setup for around $300

Depending on how much you want to spend I would go with an I3 and a cheap Z68 board and then go from there.