This is called reality; the mind filters out the parts we despise. I sound like a diva in the shower; in choir, not so much. That is why taping and recording is such a valuable way to improve.
What Gwynedd says is true, but a laptop mic and speakers don't help. Get a better mic and goof around with some of the settings (reverb, etc.) and you might be able to make yourself sound at least as good as you imagine yourself to be.