I'm confused? Does anybody end up with the 1000 one dollar dollars? It sounds like the 1000 $1 bills are just the instruments of the game (not unlike a deck of cards in poker). I want more information. The rules (as I see them) state that the other guy gets either $100 or nothing -- I don't understand. Define the problem better.

What's in it for me? Please explain my possible gain in this game -- not his.

I have no stragety before hand -- I'm not putting any money in the envelopes -- he is....
I think his worse stragety would be to but $333 in one of the envelopes (also if he is above the age of reason, he should not use any odd integer amounts in the envelopes). I think his best stragery would be to put $2 & $4 in the envelopes or maybe $124 & $248. (any two even integers where their sum is less than 372).