Move pictures accross line to time

I would like to move a picture accross a line to time.

For example, drawing a line with each end A and B respectively.
I would like to append the picture (most probably a tiny dot) to the line, starting from A, and move it to B over a certain period of time.

The problem is, how do I make the dot move exactly on the line to B, so that it also reaches B by the time I specify?

Any ideas ppl on how I can code this?

It is just math...
First you have to know how long the line is and then divide the lenght with the time. So now you know how far you have to move the dot every time constant (i.e. every second). Move the dot by changing its .left value and use the API cal GetTickCount. Do not use a timer!
(Asuming it is a horizontal line)