I can only agree IL-2 is the best but all the different versions that are published by now make it a little difficult.
The easiest way would be to get IL-2 Sturmovik 1946 DVD set.
This includes Forgotten Battles, Ace Expansion Pack and Pacific Fighters and will bring you to v4.07m in one go - then download the free 4.08mpatch (144MB) from
http://www.gamershell.com (just search for 4.08 and select the 144MB game patch, not the 125 MB dedicated server patch)
Sturmovik 1946 can be purchased in retail shops in Europe and Australia. For the US you will have to buy it online for now. I would advice NWS Online shop (see link below my sig).