Hi Tony, yeah these guys are wicked. In terms of the parts i'm going for they keep changing all the time but heres so far -
Gigabyte GA P35-S3, iP35 Express, S 775, PCI-E (x16), DDR2 1066/800/667/533, SATA II, SATA RAID, ATX £59.59 £70.02
Intel Core 2 Duo E4300, Socket 775, 1.80 GHz, 800MHz FSB, Allendale Core, 2MB Cache, Retail £61.89 £72.72
2Gb (2X1GB) Corsair TwinX XMS2, DDR2 PC5400 (667), 240 Pin, Non-ECC Unbuffered, CAS 4-4-4-12 £39.54 £46.46
Samsung SH-S182M/BEBN 18x DVD±R, 8x DVD±DL, DVD+RW x8/-RW x6, DVD-RAM x12, IDE, Black, OEM, LS £15.99 £18.79
Logitech White Wireless Desktop PRO Keyboard & Mouse £7.99 £9.39
250 Gb Samsung SP2504C SpinPoint P120, SATA300, 7200 rpm, 8MB Cache, 9.0 ms, NCQ £31.98 £37.58
530W Hiper HPU-4M530 SLi Ready Black ATX2.2/BTX SATAx2 PCI-Ex2 £36.89 £43.35
Arctic Cooling Freezer 7 Pro - P4 up to 4.4GHz - S775 Dual Core / Core2Duo Ready £10.35 £12.16
Arctic Silver 5 Thermal Compound for CPU and Chipset Coolers £3.79 £4.45
Microsoft Windows Vista Home Premium 32Bit 1Pk OEM (DVD) £54.89 £64.50
Antec Nine Hundred Ultimate Gamer Case w/o PSU £57.99 £68.14
320MB EVGA 8800GTS, PCI-E (x16), Mem 1600MHz, GPU 500MHz, 96 Streams, 2x Dual Link DVI-I/HDTV
These parts are all from Scan.co.uk in terms of cost this has risen above £500 but the case and the graphics are a bit of a luxury could cut cost there. Also i'm holding off buying until july as apparentcy CPU's are going to drop in price.
the cooler and paste are only needed if you plan to overclock otherwise the stock cooler will be fine.
Also if you're not going for a 8800 GTS then I think a cheaper PSU could be bought although it seems important not to scrimp too much on a PSU.
if you're buying now, that processor ram and motherboard are a good place to start good value and easily OCed Im told.