You're a student? You could sell some stuff? Would be best to grab a good CPU first - your current one would seriously constrain a capable graphics card. Card would work, and you'd get some of the benefit, but probably not all of it (depending on what you buy). Grab a decent CPU now though (maybe a Core i3 if you're on a tight budget) and then you can combine that with a capable graphics card.
EDIT: That said, new CPU would also require a new motherboard. How much money can you put towards it? Too late to just get a refund?