Can anyone recommend any computers for me? They have to be from the UK because that's where I live. I like to play lots of games and do a fair bit of watching videos online. I also want to be able to create good videos without lag. My price range is £700 and under. I could stretch to £800 but it would have to be one hell of a computer for that. Anyone?

Custom or Pre-Built?

If you want a good quality one that you can customize: www.arbico.co.uk
They deal a good range of computers and it's easy to customize them, they come with a warrenty, so you'll void it if you open the case.