The front audio ports come right from your on board audio card via a couple cables to the front hub on your case. You can change this of course. Disconnect the wire coming from the front port going to the motherboard. Now take this wire and attach it to your new soundcard. Most cards will have the pins for a front audio source. Refer to the soundcards manual to double check. You can really keep the onboard audio card enabled and have two soundcards, just change the defaults in windows.
