I'm hoping somebody could tell me how to do this chart:

I have several scheduled tasks that start at different
times and run for various durations of time. I'd like to
create a chart with the scheduled times as the Y axis and
durations as the X axis. I'd like to have bars (or lines,
etc.) that fill in for the duration. So the end result
will be something where I can see from a glance how many
of these processes are overlapping.

Any ideas?
tod