implementing stylus drag

I would like to know if this is the way I should go about this:

I'm using embedded visual c++ 4.0 and I'd like to be able to display a new cursor on the screen when I hold the stylus down for a second or two. Then if I continue to hold the stylus down I can move it across the screen and once it is lifted I would like to be able to calculate its velocity vector(i.e. speed, direction).

So, currently my plan is to use the WM_LBUTTONDOWN and WM_LBUTTONUP messages plus a timer and do this calculation manually. I'm thinking there will be a lot of error in that however so does anyone else know of a better way?