Decent build for less than 400 GBP

Check this youtube http://www.youtube.com/watch?v=S6FD1b-tYkk

Build a Gaming PC for $350 - February 2013

I think this will do you good for all your light gamings. In fact they'll run mostly all of the games in the world at least in medium settings.

But it is important to know exactly what kind of games you want to play. What do you define by light gaming? If it is World of Warcraft, Torchlight 2, NBA 2K13, Far Cry 1. That may be considered light gaming. But if you are up for Battlefield 3, Far Cry 3, Crysis 3, etc and you want to max them out. Then a £400 computer won't be enough. 

Unless of-course you have the existing components like RAM, Power Supply and Hard Drive. Then your building may become much cheaper. But if you're buying all of the stuff then it will cost you money.

£400 is pretty low. An extra £50 - £100 would make a big difference.

Add another £100 and you would get a fairly decent PC.

I have an OS, HDD and DVD drive.SpaceCat00