You can do better than that. A quick look about.
Dino PC. I know it is £49 over budget but you can change the case and RAM and PSU and that will bring it under a grand.
Chillblast Fusion Batwing. Has not got as good a graphic card as the Dino PC but still a fair set up.
Chillblast Fusion Rocket. Very nice rig.
There are others but have a look yourself,if you see anything you like post back.