kind of a vague question, as you do not give specific things you want.
Some specific questions you need to answer are:
5.1 sound or lower/higher?
Can my soundcard support more than 2.1 speakers? 5.1? 6.1? Does my sound card support digital (S/PDIF optical audio) or analog (1/4" headphone jack/ individual channel plugs)
Do I need anything else besides 2.1 sound? Do I have room for more than 2 speakers and a subwoofer?
What am I going to use these speakers for?
Do I have any existing stereo speakers for something like a home theater that I can use?
(MOST IMPORTANT) What is my budget?
