Sound card advice

My headphones have recently given out, which gives me a reason to splurge for quality headphones to last a while. I plan to purchase Sennheiser HD 558 headphones, as I've heard many good things about it, however, I feel that I will do the headphones injustice using the on-board sound. I'm not an audiophile, but I would like to push the HD 558's to make them worth the money that I will be spending on them. What I'm stuck on is choosing the right sound card given a 100 dollar limit. I would like a sound card that is dependable in terms of build quality and software, all while sounding crisp and clear using the HD 558's. To give you some perspective, I mainly watch movies/shows, sometimes listen to music and occasionally play games. Thanks in advance!