Crash Course in Game Programming?

Lullabye_Muse asks: "I want to write a game program for an independent research class I am taking at my High School. I have until June to deliver a final product or a good demo. I'm somewhat new to programming and will be doing work at home, and at school (Linux and Windows, so cross platform OSS is best). What is the best language to learn to code games in, and do you have suggestions for any useful sites, on game programming?"