How to make or where to get a keystroke logger?

On my home computer i let my two little brothers play on it. They know the pword to get on it and they use it to play they're little online multiplayer games. But one of them is going in and trying to change my pword. Also i came in one day and found inappropriate websites had been opened. They both log on to AIM when they get on and talk to friends so i was thinking i could catch them in the act with what they log on to AIM with or see what theyre typing. Anyways i wondering if anyone could tell me the best and simplest scripting language to write a key logger. Or if you have a clean and free one i could download off of a site that would be helpfull too.