I would do this, as I teach in classrooms.
the interface PC-uController is for displaying the data on the screen of the PC, no more.
The ucontroller has more ability to catch up the time passed for each event, because it can keep "the concentration" on such event. You should do it by an interrupt of the ucontroller, afterwards it sends the time passed by the serial port.
On other hand, VB is not the appropriate tool to manage hardware, such as pins of the ports which would be perfect once a particular pin got high.

I hope it is useful.

Omar E.