I believe that Brushes made in Photoshop 7 cannot be used in PSP. I think Photoshop 6 brushes and below can. I think it's only a matter of time before Corel fixes that though :) It's always a good idea to buy PDF files instead of brushes, that way you can make your own brushes for whatever graphic program you use.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi