Clevo providers could probably do you something in this budget region
Perhaps try having a word with Kobalt
Even going on website prices, if you've already got OS and chose the no OS option rebate, you could get 2 8GB RAM machines with 320GB HDD, DVDRW, and 720QM processors for about £3040 (oh and 5870m GPUs if thats of any relevance to you, unfortunately they dont have any cheaper cards for the chassis). G860 (Clevo W860) chassis
If you didnt need I7, they have other machines cheaper of course.
Personally I'd recommend them, the aftercare is good, and even if they aren't perfect when it comes to delivery times (its a small outfit with 5 people!), they do provide a very human touch, compared to the likes of Dell, although obviously they take longer to get the machine to you (worthy trade off).
Depends on what you need really, but I would recommend dropping them an email.