Which PC for £500

Build my own PC? I am guessing that is a jokey reference to people being told not to buy an OTP?
Let me explain: I do not know what a cache is. I do not know what Linux is. I only found out today that there is a difference between having Windows XP and using Windows 7 or whatever it is that popped up after my computer crashed. I thought they were the same. Is it becoming clear how little I know? And, really, I don't even want to know, not right now anyway. I just want a computer that will do the very basic things I need and not cost much money.

laptop it is then. Laptops do basic very well (nowdays for £300 it often can do much more) and have the added bonus of being portable and use much less electricity.