Today was pay day (woop woop) and I've decided to finally buy my desktop. I was looking at building one myself, but I am willing to pay the little extra to have it build for me...saves making mistakes or contacting another geek to do it for me.
I am looking to pay between £500 and £600 and would probably add upgrades myself when games require more and more oompf. The site I've been mostly looking at is DinoPC because of its value-for-money, but I have been fooled by value for money before and bought this Acer laptop I'm typing on for £700, had its keyboard replaced in the first year under warranty, later suffered overheating problems, which then decided to die on me when out of warranty and cost me £150 to fix. So note my slight caution here.

Looking at reviews, DinoPC sounds like a good idea, I get 1 year parts & labour and 3 years labour as standard going through them. Though if somebody recommends me to steer clear of them, I'm sure I'll listen.
I've specced up this system for £550.20
AMD FX 4170 Black Edition Quad Core 4.2ghz.
Windows 8 64 Bit
8gb DDR3 1,333mhz (1x8gb)
500gb S-ATAIII 6.0gb/s
22x DVD Rewriter
NVidia Geforce GTX650 Ti 1gb
Onboard 7.1 Audio
Xigamech Asgard 382 Window - Case
450w Corsair VS PSU
To me, as somebody who's probably a few years behind on gaming PC specs the specs sound pretty damn good. Especially having a Quad Core 4.2ghz CPU, which is one hell of a step up from Dual Core 2.2ghz. Is that acceptable for the price? I know I am willing to go up to £600 if necessary, but I am trying to keep it as close to £500 as possible.
However, I am thinking Windows 8 64-bit would be pretty unnecessary (so it's £60 off of the price), I've got Windows 8 Pro 32 & 64 bit disks from when I upgraded, sure they won't be activated versions, but I can live with that for 1 month whilst waiting for my next paycheck and it'd only cost me £50. However I've never installed an OS onto a computer without a previous OS already installed, I've done it to partition drives and as an upgrade. Am I right in assuming I just stick in the disk and follow the installation instructions, or does it require a little more geekery?
Any thoughts or recommendations? (aside from, don't use Windows 8

) Maybe some sites to look at.