I want to see how long a process took. I have a start time and an end time.

I am getting it to work with the following code:

Code:
Format$(Now() - dStartTime, "HH:MM:SS")
Will this give accurate times? The process may run for 80 hours and I need this to be precise to the second.

Is there a better way? Should I look into Datediff for this?

Thanks!