I'll add to that. Your quill stem is adjustable up and down. If the length is just about right...I'd probably leave it alone for now. There are probably better places to spend money on this free bike (tires, brake pads, pedals, saddle, etc.).

Going to an adapter (about $15 on Nashbar) and more modern stem would open up a range of lengths, angles, and handlebar choices. But I'd put some miles in the saddle before going that route.