Well I wasn't trying to supply a fully usable widget and I'm definitely not a good graphics designer
So it was more like a template for your experimentation, but maybe later I can publish a widget like you want. Nevertheless, try replacing the '1 C: D:' with the '_Total' in the source code. Then start simply a file search, zipping whole C: drive or something to produce some disk load, then it should show some activity.
This is what I see in my config (work in progress, with many layers). Note the red chart in background is the disk activity; dark blue in foreground is CPU and upper vertical bar is the free memory with some tiny little fonts for net traffic and IP.