I like Creative's as well. I have the 4.1 system and my dad bought the 5.1's cuz he thought my 4.1's sounded really good. They seem to have great clarity and can take a beating (dropped mine a few times when cleaning desk)
Altec Lansing XA3021 is also a good choice. This summer I'm going to add the monitor speakers and the Altec lansing XA3021 with a new set of Altec Lansing XA3051. Could you imagine 11 speakers hooked on you computer which 2 of them are subwoofers?