What is a good and simple tool to monitor and graph free disk space over time on a windows machine?
The usual disk visualization tools are not a good fit, as the result should be an timeline of the free disk space.
You could run a script that checks the free space on the HDD you want to look at. The output could be set to append to a text file. You could then use Excel to graph it. Very low tech but fairly easy to set up and free.