Had a friend some years ago who would become somewhat ill, like you guys, while playing any motion-heavy game. First-person games drove his gut crazy. It didn't matter what type of game it was; if the view was supposed to be "your eyes" he'd get really queasy. Movies didn't bother him, and oddly enough the rest of us would get sick after ten rides on a roller coaster. He'd be fine! To get him in the same room where a computer game was being played took quite a bit. So, we tried a few things that would stop him from confusing the monitor's display with what his butt was feeling...
Wiggle in your seat. I'm not kidding! When you're driving a car or flying a plane, you get a lot of sensation through your rear. If you're sitting at a computer there is no sensation. Moving your butt reminds you that there is, in fact, no motion.
Prop your feet up on the subwoofer or a pile of books under the desk if you fly with a twisty stick. Again, reinforcement that you are not moving.
What Orig said about having a drink handy does work. That's how me and another friend cured our bud of getting sick while flying. Warm soda doesn't taste all that good (gives me a headache) so keeping a cold drink handy forces you to look away from the screen for a moment or two. A thermos of ice-tea is better than soda for two reasons. It's bigger, and it'll stay cold longer. Plus if you drink enough eventually you'll be informed that your rent is up on the tea!
Looking at the keyboard does the same thing. Especially if you're not a Class-A typist (HT, take note!

)
While it won't improve your flying skill any, and might get you shot down, try a metronome in the room. But place it just out of reach. Either you'll fall asleep or get annoyed at it and try to swat the thing.
If you want to break the habit entirely, fly offline for a few de-sensitizing runs. At first, only fly level. Take off, set up some gawd-awful low cruise power setting, and just watch things go by. Once you can do this and not get ill, try a few basic maneuvers. Light climbs, easy turns, brief looking around. Remember to look at the fixed aircraft parts (canopy frames, wingtip, headrest) as much as you watch the terrain. Remember: on the artifical horizon, blue means "This End Up". Try formation flying with the drones too; if you want to stop the drone from moving you have to make an effort at it. No cheating by plastering Natedog or Supahfry with 20mils because they won't hold still.

Use slow-steady control inputs until you can hold that drone exactly where you want it.
Turn up the AC. In a slightly cool room you have a tendency to be a bit more alert. Too much heat makes most folks groggy or slightly tired.
In the end, it wound up being a tie between the cold drink trick and the de-sensitizing trick that broke my friend of his motion sickness. Between getting used to one part moving and other parts being stationary, and the need to pee, he eventually got to the point where most motion doesn't bother him. There's still a few games he won't go near (UT and AH still makes him ill) but he can at least fly a 747 now. Slow or moderate motion doesn't bother him anymore, it's sudden or high-speed movement that makes his gut go bananas. I tried getting him into a top turret gun on our AH2 B-17 offline. The rotation and elevation didn't seem to bother him any, but once he lost the landmarks (tail, prop blur) he started getting nauseated. While he can't fly in any combat sim, or run around in most first-person shooters, he can fly an ILS in FS2k4 so smoothly it'll leave you green with envy!
-----------------------
Flakbait [Delta6]
Delta Six's Flight SchoolPut the P-61B in Aces High