I depends on if it's 4:3 stretched or black bars.
If it's back bars, the sensitivity stays exactly the same, the only difference is that you don't see what's behind the black bars.
It it's stretched, then the vertical sensitivity stays the same, while the horizontal will be faster. The 360 distance stays the same, but you will get an increased movement over your monitor (compared to the vertical axis) since the image is stretched.