where can i get a better sound system online in the uk

i'm after purchasing a better quality hifi system, preferably with surround sound...the present hifi audio system i have is not that good, it can't handle high volumes and music played through it sounds not that good.

i bought this present hifi on the argos website here in the uk, but is there anywhere else better where i could purchase a better hifi audio system with superior sound and surround sound?