Down here in Oz I have now bought three laptops and one desk top from this place:
Computers - Technology - iShopTODAY
I have chosen to stick to Dell. The machines are ex lease and have been reconditioned by Dell themselves before re selling through 'ishoptoday'. The
dearest, with postage, came in at about A$400.00, all with XP loaded. Obviously not a lot of help to you in UK but I imagine there must be similar online stores in UK or close by in other parts of Europe? Worth thinking about before you buy more RAM for an old machine, even if it will take it.
With ex lease machines you may get one that has worked for two or three years or you may get one that has sat and gathered dust, they usually have a 30 day warranty, a minimum of 1GB RAM and an 80GB hard drive, sufficient for most peoples needs who don't run large technical programmes etc.