[GerritJ9]

The original Il2 cannot be updated to 4.08, because a new engine was introduced for Forgotten Battles. IL2:1946 consists of: Forgotten Battles, Ace Expansion Pack, Pacific Fighters and all patches and addons up to 4.07m, all rolled into one DVD. 4.08m is the last official patch that has been released, with 4.09b1m, a beta, also available though the official 4.09m has not been released yet . Just buy Il2:1946 and you're practically ready to go.
Pacific Fighters as standalone can only be patched up to 4.04, but this omits a significant number of planes that also saw action in the PTO. You'd miss a LOT by restricting yourself to this.