try hotwiring the starter to see if it is the ignition switch. Put the key to the run position, then hit the starter with power straight from the battery, it should start the engine. If not, then it is your batter, or starter...
If it does. Shut the car off, and try to start it again with the key. If it doesn't, then it is your ignition switch.
hope that helps to narrow it down some for ya...