Well, I'm not that religious but I have to agree that Christmas is supposed to be about the birth of Jesus. At least, that's why we celebrate it. Jesus is God's gift to the world.
We also celebrate because we give, and it shouldn't matter how much we spend because it's always the thought that counts. Even just a card is better than nothing.
As for Santa Claus, well...I actually have this little decoration that goes out every year and it has Santa Kneeling over baby Jesus. This shows that even Santa Claus submits to the authority of Jesus.
Look out Rudolph, Santa might just replace you with the cute, magical, Christmas Kittens!