How can I tell if my soundcard accepts USB?

I'm a DJ and I'm going to buy a new mixer. I thought I should finally enter the digital age, so I've been looking at digital mixers. A lot of them state that they can be used in conjunction with computers that have a USB sound card. My laptop has 3 USB ports, but I have no idea if any of them are linked to the soundcard. Any idea how I can check?How can I tell if my soundcard accepts USB?
From what you are describing, I think they mean a sound card that connects to the laptop via a USB port. Something like this one: http://us.creative.com/products/product.鈥?/a> I believe. I would also think this would work: http://us.creative.com/products/product.鈥?/a>





None of your laptop's USB ports will be connected to the sound card.