If it's design you want to do, your best bet would be to start out as a junior artist, artist intern, concept artist, contract artist position or you could just work your way up from QA. (though that's not easy) First thing you want to do is practice drawing. Draw draw draw! You'll do it until you hate it in school and then when you finally get hired at a game studio, most will still want you to keep drawing. Some have life drawing classes at their studios to keep all the artists skills up to date. If you can't draw, that's not a problem. You can learn how and you'll get better the more you do. Google "Andrew Loomis" and start practicing his drawing techniques now.
You don't really NEED to go to game school. If you have talent and you have a game demo to back up that talent, you can get a job in the industry. But this is NO EASY TASK! The industry is very competitive and even more so now that some developers have quit or been fired recently due to the bad economy. So now you have even more experienced talent searching for the same jobs you would be. But you still have some time before you start applying to places so hopefully that won't be too much of an issue. The main thing you got to worry about is creating your demo reel, or your "portfolio." You need to show the studios hiring you that you have what it takes to create "next gen" game assets. If you have a 4 year college degree but your demo reel sucks? Forget about it. You won't be hired. But if you have a kick *** demo reel but no degree? In some cases it doesn't matter. I'm not saying to not go get that degree. If you can, please do it! It will make your life easier and its nice to be able to fall back on your degree if the game career doesn't work out. Your demo reel is the main ticket into the industry though.
If you want to do programming for computers, look for a computer science degree. You have to be pretty smart and math should come easy to you. Which is why I personally chose the art side of game development. My mind just doesn't work with numbers too well. I like the more 'creative' side, and it seems you do too.
If you want to get into 3d modelling, you're looking at software programs like Autodesk Maya, 3Ds Max, Pixologic ZBrush and Adobe Photoshop. You can also buy the game Unreal Tournament III ($30), install it onto your PC and you can play around in the Unreal Game Engine that comes with the game. A majority of games triple-A games are using this game engine. It also comes with 20+ hours of tutorials that you can watch and practice what they teach. Some of these modelling and animation programs cost thousands of dollars. So either download a "pirated" (illegal) version for your personal use to practice, or you can find free modelling programs to use. I recommend Wings 3D to start off. It's free and fairly simple to use. That's how I started out.
Keep researching and asking questions man. You're still in high school so you are in a good position right now if you already figured out this is what you want to do in life. I learned that not too long ago so I am playing catch up now.
I started a game blog that specifically will be catering to future and current game design students. I'll be posting some interviews soon on some friends who are in the industry already and may be able to give some more advice. On my site I have links to some of the more popular game design schools in North America. I also have some blog posts with more links for game design students. I suggest also visiting some of the game studios listed on my site, go to their career or job listing section, and write down the qualifications needed for that job. Once you have that, you have your road map into the industry.
Cheers man! Feel free to ask more questions I may be able to answer.