My main priority was music and I had Philips MMS430 2.1 for about 3yrs and they died recently. Their audio quality was superb. Then I bought Creative Inspire 4.1 M4500 which I didn't like at all as their sound quality was tinny and nowhere near to philips set. Finally, I bought Altec Lansing MX-5021 (THX certified)for 6.7k (now 6.3k) and believe me, the audio quality of this set is stunning and it's worth every penny.
If you don't have much 5.1 collection and if audio quality is your priority, you should really try Logitech X-2300 (for heavy bass <<hip-hop, disco, rap>>) and MX-5021 (for clean and clear audio <<indipop, india film music, pop, rock, country?>>)
X-2300 is around 8k
MX-5021 is around 6.3k
If your budget is strictly inside 5k. You better stick to the <3k range speakers.