The 5.1 speakers I am recomending will require a soundcard because its a 5.1 channel, which requires a front/rear/sub connection.
But what I am recomending is a stereo system that is 5 years old, but it is FANTASTIC for the money.
I give you...
The logitech x530: http://www.newegg.com/Product/Product.aspx?Item=N82E16836121126
Its sold out in Newegg, but there available on Amazon, Ebay and such for $50.
I must say they are simply fantastic for the price.