Here is one of my Green Tea Questions If you have some insight, let me know . . .
Why do we consider the Sabbath on Sunday instead of Saturday? I know that Sunday is Resurrection Day (the disciples met on Sunday in addition to the Saturday Sabbath – see “Lord’s Day” in Revelation 1:10 ). But, I am looking for a more practical or historical answer. Or at lest an educated guess or a witty response. Could I have researched this? Yes. Is that as fun as asking you? No.
Aaron's Angle 
Some Biblical and historical food for thought.
http://emmilglenn.wordpress.com/2009/11/18/did-the-early-church-keep-the-sabbath/
Before Constantine, the early church met of Sabbath (Saturday)
Part of my growing up years were spent in traditional Sunday church, and part were spent in Messianic congregations that met Friday evenings or Saturday mornings. In church I was taught that we worship on Sunday simply in honor of the day that Jesus rose from the dead. However, I have also read that Constantine designated Sunday as the day of worship, both to alienate the Jewish population from Christianity as well as to assimilate the large pagan population at that time who worshiped the sun-god. For that reason and others, many people I’ve known have adamantly rejected Sunday as a day of worship, stating that the only true Sabbath begins Friday evening at sundown and continues through Saturday afternoon as designated by God in Genesis. We live in a high-demand culture where many businesses must be run 7 days a week and some 24 hours a day. My personal belief is that God’s purpose in creating the sabbath was to designate a specific time to stop everything — to rest in Him and recognize that He is God. I do not believe God is as concerned with WHEN we worship Him, as much as that we DO take time from all of our business to completely focus on and worship Him.
where is your “learning blog”?
I has to do with Constantine. Look on my Learning blog under Sabbath.