First time build. Would appreciate opinion on chose components.

[Chaos_Wraith]

Over the last few weeks I have looked at computers and components because I have decided to put together a simple gaming computer for around £400-£500. I slightly understand some parts but on a whole I feel lost. I Have managed to put together what i believe to be an ok computer but as i have said i have no idea what I'm doing. I would love any and all opinions that could be given and any improvements that could be made without increasing the price to much (unless the improvement is major).

Mother board / MSI 770-C45 / £54.09
MSI 770-C45 AMD 770 Socket AM3 DDR3 Motherboard [911-7599-005] from Overclock.co.uk - Overclocking, Performance Computer Hardware, PCs and Laptops

CPU /AMD athlon X4 630 / £75.30
AMD Athlon II X4 630 Socket AM3 2.8GHz 2MB L2 Cache Retail Boxed Processor - Ebuyer

Graphics card / Sapphire HD 5550 1GB DDR3 / £73.55
Sapphire HD 5550 1GB DDR3 VGA DVI HDMI Out PCI-E Graphics Card - Ebuyer

RAM / Corsair 2GB DDR3 1333MHz / £44.00 (I know 2Gb of ram is small but i needed to lower the price a bit and i can always buy more later)Corsair 2GB DDR3 1333MHz Memory Module Unbuffered - Ebuyer

FAN / CoolerMaster Hyper TX3 / £18.50
CoolerMaster Hyper TX3 Cooler LGA775/1156/AM2/AM3 - Ebuyer

Hard disk / Seagate OEM 500GB Barracuda / £36.55
Seagate Barracuda LP ST3500412AS 500GB Hard Drive SATAII 5900rpm 16MB Cache - OEM - Ebuyer

OS / Microsoft Windows 7 Home Premium / £79.36
Microsoft Windows 7 Home Premium - Licence and media - 1 PC - OEM - DVD - 64-bit - English - Ebuyer

PSU / Thermatake 450W 80plus / £44.70
Thermatake 450W LitePower PSU - 2x SATA 1x PCI-E 80plus Bronze Certified - Ebuyer

DVD drive / Sony AD-5240S 24x DVD±RW / £15.17
Sony AD-5240S 24x DVDRW & DL SATA - OEM Black - Ebuyer

If I have missed anything off that is needed for a computer please tell me and thanks for any help that can be given.