new pc!!

hi, need help. i have some choices:
1. buy parts seperate and get someone to built me it
or buy it pre made.
i am wanting at least :
INTEL: E7400 but would like E8400
AMD: Phenom 720 but would like AMD 940
4GB RAM - 800/1066/1333
ATI: 4890 but maybe 4850x2 or 4870x2
NVIDIA: GTX 270, would like 280
any good power supply over 700W
A good lucking case
for around 600 (english pound, buying parts seperate)
AMD phenom ii 940
4GB corsair 1066 RAM
4870x2 (powercolour or more) (ebay )
Corsair 750W
500GB harddrive
JUST BASICALLY HELP ME GET A GOOD PC CHEAP NO OS NEEDED
thanks 4 help

Sometimes it's better to get someone to build the PC. While PC bought from stores would be cheap, they are often built with cheapest part and the PSU will fry itself the second you try to install a decent video card or second HD. Not to mention the mobo almost never supports any overclocking, and RAM are likely the slowest supported junk.

I would think you could get better if you went with Intel i5 + 4GB RAM + mobo for under $400 US (which is like 38 UK pennies these day ) A decent PSU, 500GB HD, and video card would probably be another $150 to $200 for a total of about $600. (or 57 UK pennies) i5 should last you a while and currently outperforms sub-$200 AMD CPUs on the market at stock speed.

Actually I don't know how much these costs in UK but if everything costs more in UK than in USA, maybe you could find a trusted friend or relative to order everything, assemble it, and send it to you?