Oh if we are talking £400 laptops well, you can totally get Pentium Dual Core laptop with Win 7 for around £375, i know this because its what i just researched and bought for someone else not long ago
IBM Lenovo G550Asus X5DIJAcer Aspire 5732Z 3GB / 250GBAcer Aspire 5732Z 4GB / 500GBCompaq Presario CQ61-424SAThe ones at Ebay are on Ebuyer site to. If you shop around you can shave upto £25 off and get some for £375 ish for the same spec, + you have sites like Scan Today Only etc, and whatever Tekheads have in stock providing its Pentium Dual Core and Windows 7.
Argos Clearance Bargains are also good on prices, they offer 12 months with New or Refurb products.
One specific cheapo lappy for under £290 inc is
Here