Bargain pre-built?

[Mercian]

Hi All,

I've toyed with the idea of building my own and been scared off by the experiences of others posted here. Plus I like the safeguard of a warranty

I've been impatiently waiting for a sub £750 pre-built on here which will provide me at least 3-4 years of trouble free gaming for my investment but as yet to haven't seen a stand out system that does it with Vista 64 included, but now I come across this bad boy and very much appreciate your opinions - would you see this as the best sub £750 pre-built with os available right now???
AMD Phenom™ II X4 940 Black Edition Quad Core Processor AM2+
Genuine Windows Vista™ Home Premium with Service Pack 1, 64-bit - English
Tower ATX Chassis + 550W PSU
ASUS M3A78 AMD Socket AM2+ Phenom ATX Mainboard
8192MB 800MHz Dual Channel DDR2 SDRAM - (4 x 2GB)
1TB (1x 1000GB) Serial ATA 2 Hard Drive with 32MB Buffer
Samsung 22x Dual Layer DVD Writer Super Format +R/-R/RW/RAM
1GB ATi HD4850 Graphics accelerator - DVI, DirectX 10.1 PCI Express 2

Man I ready to hit the buy button!

 

[Mercian]

The case, delivery and labour push that just over £700 but I guess my concern is if there are any possible lemon components that would prevent overclocking when needed. I'm going to check the case has capacity for additional fans, but is the mobo flexible for taking upgraded graphics cards down the line, and is the 4850 suitable for overclocking if needed?

As I'm sure you guess I'm a willing amateur at best