I'm not entirely sure you should go to college to become a game designer. It's not a bad idea, it just might not be the best. I work as a Technical Animator on an upcoming MMO game, and I can say that college is not the only way into this industry.
Most companies are going to have tools that only they use, that are made by their employees, and colleges aren't going to be able to teach you that stuff. They'll be able to teach you the basics of level design, probably an editor or 2 like Unreal Editor, maybe a 3D modeling program like Maya, but they aren't going to be able to teach you about any of the proprietary tools that each individual company uses. However, if you are into games, have modded games at all, or just played them a lot, you probably already know what makes a good level in a game, and the editors/mod tools are available when you purchase games that use them. (Unreal at least comes with UT3, and an older version with UT2K4.)
Also, you need to decide what 'designing' your own games means to you. Are you going to design quests/missions, levels, props, etc? Each field is going to have it's own path of getting to the end result. If you want to design levels or quests for a game, then get really good at the Unreal Editor, Cryengine, Far Cry editor, etc. at making not only levels, but also objectives.
Lastly, you can get into the games industry just by getting your foot in the door with a job like Customer Service, Game Master, or Quality Assurance. Each of those fields requires little more than a passion for gaming, and some dedication. Plus, you won't be $100,000 in debt due to student loans. Each company is going to differ on how you are treated as one of those positions, but stick with it long enough and you'll end up just where you want to be without having to throw money into a college program. Hope this helps!