Need help to buy new pieces!

[Baralaitheone]

So, i'm looking to buy new pieces for my PC. What i'm mainly after is decent upgrades within a reasonable price range, that will tweak my performance.
This is what i'm sitting on at the moment:

AMD Phenom II X4 955 3.21 GHz
4gb DDR3
ATI Radeon HD 5800
ASUS m4A78T-E

(Pardon if I write something that is irrelevant, i'm a complete noob when it comes to specs)

I have 60 FPS with customized settings ( WoW, basically everything on High without some majors like multisampling on 1x, shadow quality low ect ect..)
I bought the PC for about 2 years ago.

Any suggestions or if you need more information i'll gladly come with it!

[OhpUldum]

Need to know a budget, currency type, and location before we can offer upgrade advice.

[Baralaitheone]

Thanks for answering so quick!
Uhm, i've got a budget on about 255 Euro's, I live in Norway