for games and music /and some bass/
if you have an amp or a good soundcard - beyerdynamic DT990
also, if you like, you can go with a pair of senn 558's /good details but close to no bass/ or cal2 /jack of all trades/...
for music /and games/
rock - grado, bass - sony mdr-xb series, techno and electronica - ultrasone...
btw - you should really spend more than £20-30 on some headphones only if you have a decent sound card /or plan to get one/. in case you're going to use integrated soundcrap, there won't be much of a difference between audiophile grade £1000 headphones and random £20 tesco grade crap.