Or French. Or Swahili. Sure, it seems like a good idea, sashaying around Paris for a romantic weekend, ordering this and that with le mot juste. And theoretically it's doable: Despite what you've heard, most linguistic experts say that adults can pick up languages as easily as kids; it's just that our methods are different. Kids learn by absorbing. We learn by analyzing, which means attending regular group classes, practicing with native speakers and sitting down with language CDs. The time and effort all that requires, though, can leave you burned out before you've figured out how to correctly place your first accent.
Commit to memorizing a few common, utterly useful phrases each day online, free, at Radio Lingua's Coffee Break
and book a vacation somewhere the language is spoken, because isn't that why you've set the goal in the first place?