I realise this is the second time in a short timespan I create a thread like this, but I'm really trying to get into it 
I hope you will be as helpful as last time.
HP LP2475w 24" Widescreen LCD Monitor £424.99
Intel Core i7 920 D0 Stepping (SLBEJ) 2.66Ghz (Nehalem) (Socket LGA1366) - Retail + World In Conflict PC Game £205.99
Lian Li PC-A71B Aluminium Tower Case - Black (No PSU) £169.99
2 x XFX ATI Radeon HD 4890 XT 1024MB GDDR5 PCI-Express Graphics Card (Includes Tom Clancy's H.A.W.X. £309.98
Gigabyte GA-EX58-UD3R Intel X58 (Socket 1366) PCI-Express DDR3 Motherboard £143.99
PC Power & Cooling Silencer 910W Power Supply £126.99
OCZ Reaper 6GB (3x2GB) DDR3 PC3-15000 (1866MHz) Tri-Channel (OCZ3RPR1866C9LV6GK) £99.99
Samsung SpinPoint F1 1TB SATA-II 32MB Cache - OEM (HD103UJ) £64.99
Noctua NH-U12P SE1366 CPU Cooler (Socket LGA1366) £57.99
Razer Tarantula Advanced Gaming Keyboard - Black £52.99
Razer Copperhead Tempest Blue 2000dpi High Precision Gaming Mouse - Retail £37.98
Asus Xonar DS 7.1 PCI Sound Card (90-YAA0F0-0UAN00Z) £36.98
LG GH22NS50 22x DVD±RW SATA Dual Layer ReWriter (Black) - OEM £18.99
3 x Noctua NF-P12 Vortex-Control 120mm Quiet Case Fan - 3 Pin £51.72
Arctic Silver 5 Thermal Compound (3.5g) £6.89
Total : £1,831.56
So, what could I improve for less £? Where did I make a horrible mistake? Where am I getting ripped off?

I hope you will be as helpful as last time.
HP LP2475w 24" Widescreen LCD Monitor £424.99
Intel Core i7 920 D0 Stepping (SLBEJ) 2.66Ghz (Nehalem) (Socket LGA1366) - Retail + World In Conflict PC Game £205.99
Lian Li PC-A71B Aluminium Tower Case - Black (No PSU) £169.99
2 x XFX ATI Radeon HD 4890 XT 1024MB GDDR5 PCI-Express Graphics Card (Includes Tom Clancy's H.A.W.X. £309.98
Gigabyte GA-EX58-UD3R Intel X58 (Socket 1366) PCI-Express DDR3 Motherboard £143.99
PC Power & Cooling Silencer 910W Power Supply £126.99
OCZ Reaper 6GB (3x2GB) DDR3 PC3-15000 (1866MHz) Tri-Channel (OCZ3RPR1866C9LV6GK) £99.99
Samsung SpinPoint F1 1TB SATA-II 32MB Cache - OEM (HD103UJ) £64.99
Noctua NH-U12P SE1366 CPU Cooler (Socket LGA1366) £57.99
Razer Tarantula Advanced Gaming Keyboard - Black £52.99
Razer Copperhead Tempest Blue 2000dpi High Precision Gaming Mouse - Retail £37.98
Asus Xonar DS 7.1 PCI Sound Card (90-YAA0F0-0UAN00Z) £36.98
LG GH22NS50 22x DVD±RW SATA Dual Layer ReWriter (Black) - OEM £18.99
3 x Noctua NF-P12 Vortex-Control 120mm Quiet Case Fan - 3 Pin £51.72
Arctic Silver 5 Thermal Compound (3.5g) £6.89
Total : £1,831.56
So, what could I improve for less £? Where did I make a horrible mistake? Where am I getting ripped off?