Barry,
What I know about the use of the 200 week moving average and the 200 month moving average I read in this article about Michael Belkin...
http://www.thestreet.com/funds/supermodels/10121439.html
What got my attention about the two moving averages is that Belkin has found that they have "worked to define levels of support and resistance in every major bubble and crash he has studied over the last 100 years. A bear market bounce in a stock or commodity from its 200-month moving average to its 200-week moving average, he says, is relentless, takes about a year and ends with low volatility - all characteristic of the recent U.S. rally."
He points out that after the bubble burst in 2000 the Nasdaq found support at its 200 month moving average in October of 2002 at about 1180. He originally thought that the resulting rally would meet resistance at the Nasdaq's 200 week moving average of 2280. But he changed his mind about the Nasdaq getting that high when money supply growth started slowing. Now he thinks the Nasdaq will fall short of that target.
My main chart service is StockCharts.com. If you want an education on the use of moving averages in general and other technical indicators, they have a good "Chart School"...
http://stockcharts.com/education/
Larry