Knowing at all what your specs are would help out.
They have had dual core cpus since 2006, so that is all "dual core" tells me, and even modern dual cores are not made equal.
If you have a 3 year old computer upgrading is best, if you have a 6 year old computer then it is not worth putting any more money into it and even a low-medum end gpu would be handicaped by your computer.