My cousin also suggested overclockers.co.uk so I spent a couple of hours checking out parts and comparing prices etc. My bare maximum budget is about £700 and that is absolute maximum at the moment.
If it does make a difference the OS im planning on running is Windows 7, but I thought there was more depending on what motherboard I decided to use rather than OS. Its possible however that I could sway towards to Vista purely because of how much it costs.
Check out the other website I mentioned in my previous post. They have some cheap prices too.