I find it bizarre that people are happy to spend £200 on a vid card and then just use the built in sound from their motherboard.
Sound is a lot more subjective than video I guess...
I have a bottom-of-the-line 5.1 surround sound soundcard for a whopping $7.50(*) and a set of 5.1 logitech speakers that were about $50 or so, and to my ears I don't hear much room for improvement.
Now, what I don't get is how some people spend bazillions of dollars on a PC, and then skimp out on spending the extra 10 bucks to get an optical mouse.
(*) Only reason I didn't use the onboard sound is that, like most, in 5.1 surround sound mode you cannot have a microphone plugged in at the same time. Very inconvenient when you also do voice chat on the PC. That plugin card had the three speaker hookups as well as line-in and microphone, plus it gave me a midi-port to hook up a joystick.
And on the subject of broken speakers: check your cables as well. My last pair of speakers got fried after one of my cats bit through the 18V DC power cable.