If you download from the History center, you get all M1 quotes from 1999 to end of september 2006. Then if you close the terminal and reopen it and open a chart on that pair, the broker' feed will fill the quotes from 1/10/2006 up to now. But there is a bug and for some brokers/pairs: all october is missed, so you have a big hole in your history.
Other thing : the historical datas downloaded from the History center are generics : they are not filtered by your broker, so they are totally useless to backtests some fast strategies.