The two popular series' of soundcards are the Creative X-Fi series and the ASUS Xonar series. Generally, the Xonar are favored for music while the X-Fi are favored for Gaming. Get whatever fits your budget
I will be purchasing a Xonar DG here soon for a couple reasons. The first being that is is cheap. It can sometimes be purchased for under $20 after rebate. Also, it has a headphone amp able to drive up to 150Ohms. Lastly, in this blind listening test to various songs, it was actually preferred over onboard sound and the Xonar Xense which is priced at $250+, a majority of the time.
But I am a music fanatic so that's why I am going for the Xonar