I'm looking to get some input on what would be best to upgrade in my current system, given that Christmas is slowly coming up etc.

This is my current system, bought roughly 2 years ago:

CPU: Intel Core i5-2500 3,3 Ghz
CPU Cooler: I think this is simply the stock CPU cooler, I don't know its name
Motherboard: Asus P8H67-M LE Socket 1155
Ram: 8 GB DDR3 Ram 1333 Mhz
Storage: 1 TB HDD
GPU: Radeon HD 6850 1024 MB
PSU: BeQuiet 450W 80Plus Bronze

Budget: Lets say 300€. I'm looking to make some improvements without spending/getting other people to spend all that much money; I mainly want smooth performance on current releases for the foreseeable future
Resolution: 1920*1080
Games / Settings Desired: I'm usually content with high, but I like Ultra in WoW.
Any other intensive software or special things you do: no
Country: Germany (but simply suggesting useful parts is fine, I can google)
Parts that can be reused: see above
Do you need an OS?: no
Do you need peripherals (e.g. monitor, mouse, keyboard, speakers, etc)?: no

I hope I did this right - thank you for your time and help in advance! If more information is needed I will try to provide it.