the FUD about how many coins he got is based on people adding together all the different addresses of the coins from january 2009 forward for a few months.. but im sad to say that satoshi, hal finney, and a few other notable names all were mining at the same time. it was not just satoshi by himself.
The estimate of Satoshi's bitcoin holdings (980k) is based on analysis of the data in the actual blocks, not just some sort of address guessing. Bottom line, Satoshi was a persistent miner with significant hardware. He mined a lot of bitcoins which are largely unspent.
http://bitslog.wordpress.com/2013/04/24/satoshi-s-fortune-a-more-accurate-figure/