Pharaoh wasn't jewish though. (just to be picky
To be honest, I don't really care if prayer works or not.. if it works because its a placebo or because one of the gods answers.. prayer is one of the few religious issues that DOESN'T generally impact negatively on the rest of us.
If people want to believe in prayer and it makes them feel better then let them. As long as it doesn't interfere with anyone else it is fine with me.
there is however no evidence whatsoever it works.. so its entirely down to your beliefs.