If you're listening to mostly music, you might be better off sticking with a better quality 2.1 system than a lower quality 5.1, but if you really want the surround sound effect, then that's your call. The only problem is most laptops don't really have sound cards that handle surround sound, so to have proper surround sound you would either need a speaker set with built in surround encoding (ex. logitech z680's), speaker set with separate decoder box (ex. creative DDTS-100), or a break out USB sound card (ex. audigy 2 nx). All of those seem to be out of your price range, so I'd stick with a stereo setup. =)
As for a good setup, I'm not too familiar with 2.1 in that price range but I heard many people love the
Altec Lansing ATP3. Speak up if you ever want to boost your budget and invest in something a bit better. =)