Speaker Issues

Hello, I'm a relative neophyte to the computer world so be kind, but I have a problem and need help.
I recently bought a new computer from Futureshop:
http://www.futureshop.ca/catalog/proddetail.asp?logon=&langid=EN&sku_id=0665000FS10107120&catid=
and have plugged into it my old speakers. The speakers are Altec Lansing VS2121, including two small speakers and a subwoofer.
My problem is this: they won't work with my computer. I've checked the sliders/mute buttons on the computer, tried every different audio jack on the computer, I've hooked the speakers up to an ipod to check them (they're fine), and I've updated the drivers several times with slightly different Realtek drivers to no avail. For some reason the sound is so heavily distorted that it sounds like rubbing velcro on a microphone (I hope that makes sense).
I hope someone can help, I've posted this before in another forum and so far have had no luck and I'm getting pretty frustrated. Thanks in advance.

Other forum post in case it helps:
http://www.computing.net/answers/hardware/speaker-trouble/52749.html