Go to ebay and check out HP MarketPlace UK
This is were Hewlett Packard sell there factory returns and refurbished laptops and PC's.
Around 18 months ago I bought a Compaq Presario Lap Tap that was on sale in PC World and others at £950 to £1000. I paid just under £600 including full 12 month warranty and genuine software that can be updated etc etc Never had a problem with the machine,and if I did I know I could get parts for it.
Not a lot on sale at the moment as it's Christmas and this is a business seller so it's worth while checking out the items for sale in the New Year.
They have this for sale at the moment, looks good and in your budget at the moment ...
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=260068789325&ru=http%3 A%2F%2Fsearch.ebay.co.uk%3A80%2Fsearch%2Fsearch.dl l%3Ffrom%3DR40%26satitle%3D260068789325%26fvi%3D1