How about doing a lil overclocking?
LN11596 2Gb (2X1Gb) Corsair TwinX XMS2, DDR2 PC6400 (800), 240 Pin, Non-ECC Unbuffered, CAS 5-5-5-12 £193.45
LN15198 AKASA Zen case - Black Silent Cool Midi-ATX Computing case w/2 silent 12cm fnas & front I/O ports £31.71
LN14947 20" Viewsonic VA2012, Widescreen TFT, 1680x1050, 8 ms, 600:1, 300 cd/m2, Silver/Black, Speakers £249.09
LN15102 Intel Core 2 Duo E6300 S775, 1.86Ghz, 1066Mhz FSB, Conroe Core, 2M Cache OEM (w/o Heat Sink Fan) £120.66
LN13080 Arctic Cooling Freezer 7 Pro - P4 up to 4.4GHz - S775 Dual Core / Core2Duo Ready £17.57
LN15603 256MB Leadtek 7900GS PCI-E (x16), Mem 1320 MHz, GPU 450 MHz, 20 Pipes, 2x Dual Link DVI-I/HDTV £123.96
LN15451 MSI P965NEO-F, i965, S775, PCI-E (x16), DDR2 533/667/800, SATA II, ATX £70.37
Total £825