so i been thinking that i need new gaming rig because mine is now like 5 years old Intel core 2 quad Q6600 2.4ghz 4gb ram and hd 6450 i been thinking to get new one and i have now idea which one to get.
so the price i want to pay for pc is 400 pounds no dollars i live in UK
Problem is that you have an old 775 socket motherboard. Your video card is still viable (ish) but will not max out any new games. If you are happy with that, then your decision is AMD or Intel. You can pick up a decent gaming CPU/motherboard/ memory combo (prices are US) :
AMD: 970 Pro3 ASROCK; $69, FX6100 $119, 8GB DDr3 1600 $53 total $241
This system will run most games well, but will not max out all games due to your older GPU and certain architectural differences between AMD systems and intel systems.
Intel: ASRock Z77 pro3 $89, i5 2310 $174, 8gb DDR3 1600 $53 Total: $ 316
A bit more expensive, but you get PCIe 3.0, better architecture and faster game performance. Yes, your card will run, but not any faster. I recommend a good PCIe 3.0 video card, a HD 7770 for $150 is a good mid range choice. This will run all games well (but not maxed) and keep you from upgrading for awhile.
If you intend to overclock, you will need a K series processor for $220 and a good CPU cooler.