New cheap gaming build advice please

Hello all,
I am planning on building a cheap ($650-700, £450-500) gaming pc over the summer. I decided I would pick out a build and get your opinions on it. There very well may be errors, incompatabilities etc, so please read it carefully . I have gone slightly over my budget, so any suggestions to bring it down would be awesome. I have chosen a motherboard that supports DDR3 ram, which I am undecided on at the moment and seems to be quite expensive. I was also unsure how much would be necessary.

What I need it for

I plan on playing games such as GTA IV, Bad company 2 and other intensive games at a resoloution of 1920x1080. I am aware i will need pretty good specs, however I DO NOT need to play at max settings, mid range is fine, although I do want to keep my resoloution.

The build I have chosen doesnt include a case, so I need advice on what I can change for what, why I don't need something etc. I am fairly sure you have guessed I am hardly and expert in these matters, however I am interested in building a computer, and love playing games on 'em!

Thanks a lot!

The build


Motherboard
http://www.ebuyer.com/product/219204

Cpu
http://www.ebuyer.com/product/186428

Gpu
http://www.ebuyer.com/product/199404

Ram (There may be issues here)
http://www.ebuyer.com/product/178942
http://www.ebuyer.com/product/159922

PSU
http://www.ebuyer.com/product/190751

HD
http://www.ebuyer.com/product/159393

Dvd Drive
http://www.ebuyer.com/product/149313

Am I missing anything?

Drop to a 925 or even a 630 chip
Hit 2 x 2 Crucial Ball CL7 1333
http://www.ebuyer.com/product/179278
NZXT Beta EVO for case?
SATA DVDRW not IDE

Ya - SATA interface DVDRW You are welcomed ^^

Ok, I am beginning to think I will use my currect hard drive with the new build. Is this a sensible Idea? will the operating system (vista) still work etc. Are there any downsides to this?

it probably won't. unless you uninstall most of the drivers before plugging in to new system. but 90% you will get random system crashes, due to driver conflicts.

You are welcomed and happy shopping/building ^^