Guys.. you aren't understanding here...
They make two versions of these headphones... one type that plugs into the soundcard, and another that uses a USB Interface and is essentially a USB soundcard of its own.
The ones he's getting is the type that connects to the back of an existing soundcard. YES IT DOES have a USB connector, but this USB connector is used ONLY to power up the amplifier, NOT to communicate with the computer.
I have the same exact headphones except mine DO use the USB interface however I have yet to notice any deterioration of computer performance in using them.. even before I built my new system. They sound great.. they work great... and when I plug them it, it 'turns off' the onboard sound and engages them instead.