Does your sound card have recording and playback mixers like Sound Blaster rubbish used to? If so, check that you don't have a couple of channels both enabled for playback--maybe "mic in" and "what you hear" or any of an infinite number of combinations that would playback your recording mic twice.
But I agree--your sound card is totally unsuitable for any form of serious recording.
The pessimist sees the glass as half empty. The optimist sees it as half full. The realist just drains the darn thing and gets a refill!