Exactly what are you looking to upgrade, other than the gpu? Getting the latest processors will entail changing the motherboard as well. I don't think RAM is as issue since you already have 8 GB. What is your upgrade budget?
These are some good GPUs which could run on your current PSU:
There's no problem with the components you picked, but a GTX 560 for heavy gaming is not a good idea, games are more demanding than before, a 2GB of VRAM became a must, put up some money and try to get at least HD 7850 or HD 7870.
For the motherboard, any Z77 or Z68 will carry the 2500K, and it's a great gaming chip by the way.
For HDD, a 500GB WD Blue or a 1TB would be so sweet.
Also, a nice SSD will give you a good boost for gaming and other applications.