Hp do a desktop with an ntel Core i7 CPU, 8Gb of Ram and 2 x 1Tb hard disks as well as the usual stuff like a Blu-ray reader and a DVD burner for just over £1100. Anything around that sort of spec will fly.
Of course, it can be useful talking to a good small PC store as they may be able to build you a system as good for less, but one that isn't "restricted" in the motherboard department like so many brand name PC's are.