When wondering whether to upgrade or not, ask yourself this question:
If the answer is "yes", then you should think about replacing the bit that is broken. If the answer is "no", ask yourself this question:Is anything broken?
If the answer is "yes", then you do not need to upgrade. If "no", then you need to upgrade.Does my computer do what I need it to do?
Then you need to decide on a budget (with a limit that you will definitely never go over, not even if there is this really awesome thing for 20 bucks extra). That will define the upper limits of your new purchase. Only when you have done this should you ask the question:
What kind of computer should I build?