First of all, this thread should be in the Hardware QnA section. I don't have much expertise in the audio department, so I wouldn't be able to contribute much to this thread but in reply to Gollum, here's what I've got.
Why do you want to buy a sound card. The on board sound card is enough for driving any 2.1speaker. Also buying a 5.1card for 2.1 makes no sense and would be a waste of money.
You, sir, are just trolling around. From what I gather from your posts, mostly you have no clue to what you are talking about. Currently, I own an Altec Lansing MX-5021 2.1 speaker system and a Creative Sound Blaster X-Fi Titanium sound card. The sound that this combo produces can never be matched by an onboard sound card. Not by the one I have on my Gigabyte 790FX-GD70 at least. You need a good discrete sound card to go along with a high range speaker system.
So, before you start hopping in the mud, be sure to wear the right shoes.