I am currently running 10.5.7 on my Dell Mini 9. The vertical speed is much faster than horizontal speed of the mouse movement (not scrolling) on the touch pad. I think this has something to do with the touch pad being rectangular vs traditional square size on older laptops. Since OSX sees the touchpad as a square shape the horizontal speed is slower because the actual touch pad is wider. You can easily check this by moving your finger in a circular motion and you will see the mouse moving in a vertical oval shape instead of following the circular path you are doing with your finger.
I am thinking to upgrade/clean install to 10.6.1.
1) Is the mouse pad issue fixed, or same problem?
2) Is there an alternate mouse driver that fixes the ratio of mouse speed?