I just picked up a MSI 620 and its really nice. I cant name any sites but you can pick one up just £8 over £400 with Windows 7 64bit and 2Gb of ram, i3 350, 250Gb disk.
I actually got the MSI 620 without the operating system (Only £379) and I got 3Gb of ram instead, 320Gb harddisk and an i3-370m chip. Seems nice so far, got it running ubuntu and Windows 7 dual boot. Liking the chiclet keyboard.
£379 was the most I could afford and the only other laptops I could find with an i3 at this price range was the Samsung E452-JA01UKor the Lenovo G560 both which look a nice deal. I just liked the look of the MSI 620 and im fan of the chiclet keyboards.
Hope that helps.