First of all let me say that every parent has the right to tell or not to tell their kids about Santa. We chose to not tell our kids that Santa is real for religious reasons. We want our children to be able to completely trust us, especially when it comes to God. My husband really was hurt by the Santa myth. His parents went out of their way to prove that he was real. So, naturally, he believed them. When they couldn't answer all of his questions about Santa, they finally told him the truth...Santa is not real. Consequently, he questioned the reality of Jesus. When his parents reassured him that Jesus was real, he said "but you said Santa was real, so was is the truth?" They had a very difficult time proving that they were't lying "this time".
Needless to say, he was very confused and not sure what to believe. He did recover eventually, got saved at age 9 and is now a pastor. We opted to spare our kids this trouble.
I'm just saying be careful what you tell your kids. Be honest with them when they ask questions. Our kids knew that Santa was not real. We also told our kids not to tell other kids that Santa wasn't real. They are well adjusted, Jesus loving, parent believing kids.