You have got a nice CPU, and nice RAM.
You could get yourself a new HDD, 150 gb is not enough nowadays.
If you're a gamer I would suggest you get a better GPU, maybe a GPU from the
Radeon HD 5xxx or 6xxx series?
I don't know how much money you have to use, and I do not know what motherboard you have, if you could tell me, I would probably be able to help.