Or you can go for Ivy bridge and use the integrated graphics if you are not gaming ?
to add to the questions from doom, do you need an o/s, monitors, keyboard, mouse etc.
basic rig:
1 x Intel Core i7-2600K 3.40GHz (Sandybridge) Socket LGA1155 Processor - Retail £227.99
1 x MSI GeForce GTX 560 1024MB GDDR5 PCI-Express Graphics Card £129.95
1 x Crucial RealSSD M4 128GB 2.5" SATA 6Gb/s Solid State Hard Drive (CT128M4SSD2) £99.95
1 x Gigabyte Z77-D3H Intel Z77 (Socket 1155) DDR3 Motherboard £79.99
1 x Seagate Barracuda 7200.12 500GB SATA 6Gb/s 16MB Cache - OEM (ST500DM002) £59.99
1 x Zalman Z9 Plus Tower Case with Fan Controller - Black £49.99
1 x OCZ ZS Series 550W '80 Plus Bronze' Power Supply £46.98
2 x Kingston HyperX RED Limited Edition 8GB (2x4GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (KHX1600C9D3B1RK2/8GX) £43.99 (£87.98)
1 x Sony Optiarc AD-5280S 24x DVD±RW SATA ReWriter (Black) - OEM £14.99
Total : £812.81 (includes shipping : £12.50).
This spec is good but I would recommend the i7 Ivy Bridge over the i7 Sandy personally.