I'm currently working on a top down shooter game, and the speed I move the objects at is scaled by gameTime.ElapsedGameTime.Milliseconds to make sure they move at a constant speed independent of the framerate.  However, sometimes there are stutters and they don't always seem to move at a constant speed.  I thought this could be cause by sudden drops in the framerate so I tried smoothing the value with previous frametimes, but this still does not give the desired result.  I also remember reading somewhere that GameTime is not very accurate on the Xbox360 so I tried to use DateTime.UtcNow.Ticks instead, but this does not seem to make any difference at all.  Any thoughs on this issue would be greatly appreciated.

Regards,
Dennis