I really don't want to risk it, and wouldn't want to fit the parts in myself as i don't know how to. Hence why i've opted to buy a desktop already made.
I've altered the cougar extreme package so i can invest in a better PSU and cooler, and stay within my budget:
Intel Core 2 Quad Q9550 2.83 Ghz 12Mb Cache,
Zalman CNPS7000C-ALCU heatsink,
4Gb Corsair Memory DDR2 800 (2 x 2gb),
500GB SATA Hard Drive,
AM3 Asus M4N78-SE - DDR2 1066x2 720d chipset,
ATI 4870 1024MB PCI Express DDR DVI,
Elite 330 Black Midi Case Window No PSU RC-330K-KWPC-GP,
Cooler Master 500W PSU,
DVD+/- RW - 20X (pioneer 116DBK),
No Floppy Disk Drive, Integrated Sound Card, Intergrated Monitor Speakers, No printer,
No Operating System
Alternatively i can also get this PC:
Cube247 - Zuben ST20
Microsoft Windows 7 Home Premium
Intel Core 4 Quad Q9550 Processor
4096MB Corsair DDR II Memory
1000GB SATA II Seagate Ultra Fast Hard Disk Space
NEC 7200 Multi Format DVD/CD ReWriter
ATI Radeon 4870 Performance Graphics
5.1 High Definition Surround Sound
Intel Deluxe Motherboard
Multi Format Memory Card Reader
10/100 Ethernet LAN
12 x USB2 Ports
12 Month Classic Warranty
Microsoft Office 60 Day Trial
Microsoft Windows Live Essentials