historical data.

If you run the numbers over the same total time but from Jan. 2000 -> June 2010 you end up with $236,612.23 and a negative rate of return. A lot matters where you are in history etc. In order to overcome this many companies use Monte Carlo simulations. . . e.g. they run random fluctuations in returns etc. over the time span projected. Then they do that another 1,000 times and take the averages.

I don't know what you are attempting to accomplish. But I really like the financial retirement projections of personalcapital.com.

It runs a conservative estimate. Runs I think 1,000 Monte Carlo simulations. And then shows you the Median return and the worst 10% return. Anything above median is bonus. But it allows you to see possible fluctuations of investments and how slight changes may affect your retirement.