Actually, inquiries only affect your score for a limited time period... I believe three to six months. They are by far the least damaging.
However, it is amazing but one inquiry can drop your score by up to 5 points. I had one drop mine by three points... (curiosity... I ran my score, did an instant application for a charge card, was approved, and ran my score again immediately before the new card's approval could be entered to my score)