Hmm...I'm not really sure why people go to church on Sunday.
Do Jews respect the Sabbath on Saturday then? I'm not sure of that.
Some people say that Jesus broke the Sabbath day law all the time, here are examples that people give about Jesus breaking the law (at least in the Pharisees eyes).
http://www.bible-truth.net/sabbathseries/abolish.htmlThis link talks about 'How' to keep the Sabbath though. I am not really sure if Christians are supposed to respect a Sabbath day or not though. The Ten Commandments were originally meant for the Jews and Jesus basically restated a majority of them in the Beatitudes (I think he only left out the Sabbath and having only one God laws).
I think maybe Christians changed it to Sunday to respect the day Jesus was resurrected like you said, instead of respecting the day God rested on after creating the Earth.
I don't really know though. I'm just drawing some of my own conclusions really. xD