How many years of college does it take to become a video game designer?

It really depends.

A friend of mine wants to be a game designer; and will walk to all ends of the earth to become one.

She has currently done 2 or 3 years in an arts degree; but she is transferring to another university to actually do a game design course.

I think you need at least a 3 year course if you wanted a job, mainly for the fact you would need to know a few programming languages or how to model in 3D space, or how to make/alter game engines and the like.

And it is a very..i repeat.. VERY sought after job. You would have to bring something very special with you to actually get a job with someone; or you could just try start your own games company. But yeah, its a quite slit-throat industry; and you would want to have a few years experience under your belt + some kind of degree or something to say your better than the rest.