Opinion on 2 different custom built desktops.

Hey,
I'm looking into buying a new computer for around the £500 price range.
I've been looking at a few custion build websites and got 2 different builds from 2 different websites and was wondering if you could help me in telling the difference between the two.

1st..
Processor - AMD PHENOM 9750 QUAD CORE 2.4GHZ 4MB CACHE
Memory - 2Gb Corsair Memory DDR2 800 2x1Gb
Primary Storage - 160GB SATA Hard Drive
Power Supply - Standard 400Watt PSU
Graphics - 512Mb 8600GT Nvidia DDR DVI |or| 512Mb ATI HD 2600PRO graphics card DX10?
Motherboard - AM2 - MSI K9N-Neo-V3 1000FSB - DDR2 800x4-nForce 560
Sounds - Integrated Sound Card
Operating System - Microsoft Windows Vista Home Basic (OEM)


2nd..
Processor - Intel® Core™2 Quad Q6600 (4 X 2.40GHz) 1066MHz FSB/8MB Cache
Memory - 2GB CORSAIR XMS2 800MHz
Primary Storage - 160GB SERIAL ATA II HARD DRIVE WITH 8MB CACHE (7,200rpm)
Power Supply - 300W Dual Rail PSU + 120mm Case Fan
Graphics - 1024MB GEFORCE 8600GT PCI Express + DVI + TV-OUT
Motherboard - ASUS® P5N-MX: DDR2, S-ATA II, 1 x PCI-E x16, 2 PCI, etc
Sounds - ONBOARD 6 CHANNEL (5.1) HIGH DEF AUDIO (AS STANDARD)
Operating System - Genuine Windows Vista™ Home Premium 64-bit Edition + SP1, CD

So, which one would you choose? And why?

Thanks a lot for your time.