Gaming Computer under £650...

Hello,

I would like to ask what is the best gaming computer in the price range of £500-£650?

I would prefer a computer which is not custom built because I have no experience and, at least, has the following components: an Intel i3 or i5 processor, Nvidia Geforce GTS 250 or GTX 260, 500 GB Hard drive and 4 GB of RAM.
It would be great if it also has Windows 7 and a monitor, keyboard and mouse...

So far I have found the Acer Aspire X5900: http://www.play.com/PC/PCs/4-/14794230/Acer-Aspire-X590...$ja=tsid:11518%7Ccc:%7Cprd:14794230%7Ccat:Computers

However, the graphics are lower than what I would like and I am not sure whether the computer's motherboard would support a Nvidia GTS 250 graphics card...


Note-

I am only a casual gamer and therefore the computer will mostly be used to play Just Cause 2 and possibly a few other games. Therefore, I would like the PC to meet the recommended specs for Just Cause 2...