I want to buy some new speakers, what do i go for?

Okey, i am 15 and i dont earn much money, so i am trying to get a decent speaker system and i have about �120 quid, i am thinking of getting the Logitech Z-2300's but also the Logitech Z-5500's look really good, is it worth the save? and is there any other speakers u would advise?? i am really into the whole as much b as possible thing lol, thanks :)