If you dont game and the PC has onboard sound(as most motherboards do nowadays) then I would suggest you might not need a soundcard at all.
Certainly onboard sound will manage an internet radio broadcast very well.
It would then all come down to how much you have to spend and what importance you place on quality of CD playback. If you decide that the onboard sound is not sufficient (try Toms Hardware Guide at click here for a recent article about onboard vs soundcard) you will have a choice of many different cards. Current favourite for music playback according to most reviews seeems to be Audigy 2, but that is around £70/£80. You could take a look for an older Audigy 1 or even a Soundblaster Live 5.1, which would also allow you to upgrade at a future time to 5.1 speakers for DVD or gaming. PC World are currently selling SBLive 5.1 retail boxes for 29.99 to lower stock levels - you might get cheaper than that from an online retailer or by buying an OEM version.