That is a good question that a lot of people have. It is not a contradiction, but it is often misunderstood. When a person surrenders their life to Jesus Christ, they do in fact gain the gift of salvation which is marked by the indwelling of the Holy Spirit. They also are given by the Holy Spirit a gift or gifts depending on His plan for their life.
The baptism of the Holy Spirit is a separate occurrence in which we are asking the Holy Spirit to grant us with a fresh empowerment for the upcoming ministry in our lives. This often can come with new gifts or gifts that we have had in the past or gives previously granted, but not used. (The Holy Spirit can grant a gift for a specific time or event, but He is fully capable of granting a gift for a lifetime. It depends on what will gain Him the most glory.)
Bible College Director