Yes, it's as simple as swapping the stem out. Your headset is a threaded headset, so the stem does not actually mount the fork to the frame -- so you're free to swap stems around as you see fit without any worries about steerer tube length, etc. If your adjustable stem is set exactly where you want it, then you'll need to find a replacement stem that's about the same size/shape in terms of angle, reach, etc.

You have two routes:

A) You can get a standard quill stem similar to yours, either adjustable or fixed, and use it. This is not the most common size for quill stems (1" is most common), but you should have good enough selection. I've never shopped stems by brand -- I'd use whatever is convenient. I have a polished Zoom adjustable stem on my wife's 7100, and it's attractive enough (it matches her polished riser handlebar).

B) You can get an adapter that will insert into your steerer tube that is basically a smooth cylinder, with a widened mounting flange at the top. Going this route would allow you to use a stem designed for a threadless headset. This would be more expensive because you're buying two different pieces, but some people prefer that look.