I've been getting motion sick from FPS games ever since I can remember. If the game takes place inside building chances are I will get motion sick. Games that take place outside don't seem to bother me much if at all. It's just those enclosed environments. Wolfenstein 3D and Goldeneye 64 were the worst. Return to Castle Wolfenstein also made me motion sick. Now, games like Ghost Recon or Halo don't bother me at all.