-You can't tell anyone about it until after you win; if you don't win, you can never tell anyone about it.
-You have one week from right now to purchase any tickets. You must purchase any tickets all at once.
-Assume this is (somehow) a tax-free lump sum.
Obviously mathematically you should buy as many as possible, since the expected value of a ticket is $1 million. Practically, though, how much risk can you afford? And if you are going for it, how much cash can you round up in a week?
1 in 1000 would mean there are 1000 tix? So finance out a $1,000,000 and buy all the tix and guarantee a win. Moran.