Building a new computer, so I need some help.

I am going to build a new rig, and before I do that, I would like opinions, advices, anything to build a computer that is bang for buck, that is, lower than 750$.
I live in Serbia, so this is a good configuration that is little bellow 750$.

The components are:

ASUS P8Z68-V/GEN3

INTEL Core i5-2500K 3.3GHz Box

EVGA nVidia GeForce GTX550Ti SC

KINGSTON 4GB (2x2GB) DDR3 HyperX Blu 1600MHz CL9

CHIEFTEC CTG-500-80P 500W A80

So...what do you think???

I already have a monitor, and everything else, so this is all I need for a new computer.

I wouldn't buy a 550Ti - something like a 460 would be better.

Or even a 6850.

your good with what you choose apart from the GTX550 ti . go for a GTX 460 (http://www.newegg.com/Product/Product.aspx?Item=N82E16814125412) this a pretty sweet deal

or

a RADEON HD 6850 .

my budet was 500 $ i got RADEON HD 6850 .

Downgrade the CPU to a lesser i5 quad core so you can afford a better card like a 6850 or 460 or 6870

Ok, so I listened to you all, and I made some changes. What do you think???

MSI P67A-G45 (B3)

INTEL I5 2500K

SAPPHIRE Radeon HD 6850 (I think its Toxic)

KINGSTON 4GB (2x2GB) DDR3 HyperX Blu 1600MHz CL9

I decided to keep the 2500K, because I plan on overclocking, and buying a water cooling system later, and I got 6850, because you recommended me, and I looked at some benchmarking websites, and I also have some experience with the Radeon HD cards (I have a 4200 in my laptop), so I decided to put it on my list. And these parts would cost me less than 650$.

One more question. What PSU would be best for this rig??? Also, what is a good AMD replacement for the i5???

your new list looks good. i would try to find a way to get 8gigs of ram though