Antec makes nice cases, specifically the Antec Nine Hundred and Antec Twelve Hundred:
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129021
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129097

excellent cooling, easy to work with, high quality, looks good :D

Stack is right about PSU, it's like the heart of your computer so a bad one will cause all kinds of problems. Corsair makes quality power supplies, any of these will do but i recommend 650W or higher:
http://www.newegg.com/Store/BrandSubCategory.aspx?Brand=1459&SubCategory=58&name=Power-Supplies&Order=REVIEWS

i'm using the 750TX (first in the list) right now and would buy again

Buy a pc with awesome graphic card. Mine is not btw. T.T

thanks but the main thing im worrying about is a case that can hold everything correctly with screws and compatibility issues thanks for that man it was very helpful

16GB is overkill for any gamer. Unless you're doing video encoding or planning on running a server, 6GB is enough (even that's pushing it).

CPU/Mobo: Most games and applications don't even take advantage of all 4 cores, most take advantage of 2 at most. But since quad-cores are so cheap now days it doesn't matter all too much. The AMD Phenoms aren't bad (even though Bulldozer is coming out soon) and are pretty cheap. Decide whether you want an AMD or Intel and then choose the motherboard that supports that type of CPU.

Graphics: It depends on what games you plan on playing, at what settings, etc.

HDD: Chances are you're going to want 1TB since that's what a lot of people go after for some reason, but I can confirm that Western Digital Caviar Blacks and Samsung Spinpoint F3s are both remarkably amazing HDDs, especially with price/performance ratio. The Spinpoints are a tad bit cheaper though.

Chasis: The size depends on the motherboard (ATX/MicroATX/etc), but there's a wide selection and it mainly comes down to personal features and aesthetics.

PSU: Do not skimp out on this part. If you buy a cheap PSU it can fry everything if it fails. The wattage required depends on the rest of the components you will be installing.

Hey do you think i could get a computer for £800 Pounds or less with a 16gb ram, quad core processor, NVIDIA GeForce GTX 570 1,280MB, Thermaltake Frio and Windows 7. (no extras such as keyborad mouse and monitor ???

yea but i would end up stepping on the motherboard or something...

im very clumessy

Buy yourself a barebone kit, then buy the rest of the parts.

little xD

Here's a nice little guide

I'd be happy to help, if I knew anything about computers besides the fact that mine sucks. Good luck though.

Thanks...

ok i am plan on buying a new desktop pc and i am going to spend around £800 pounds on it and i would like some advise the pc is mainly going to be used as a gaming pc and other general stuff...

Must be in the uk and can be customised but must still include the price...

what do you suggest... ???

you can use websites like http://www.dinopc.com/

and customise it but you must send me the spec of the pc and how much it costs (£800 with a tolerance of £100)

thanks for your help...