I've looking through the topics here in this subforum, but couldn't find following tip.
At the internet you can find lots of PS brushes, with file extension ABR.
With the free tool abrViewer you can convert these brushes to .png files which you can easily use in PSP.
* Open the png file in PSP
* Export to custom brush
* Now you can use it with your brush.
Hope this tip is useful for you.