Brushes made with PS7 can be used in either PS7 or PSCS. Brushes made with PSCS don't work in PS7. This is a generalized statement, as perhaps there is the rare exception. Not sure about actions or styles, as Ive never tried those (gone back to PS7 until they fix what they broke). The brush engine in both are the same, except for the one feature of flipping the brush on the X and Y axis in CS. Adobe has taken the move against backward compatibility in there major software (Indesign,Illustrator,and PS),I guess in an effort to keep sales moving forward. Bottom line.update your brushes in PS7. SWAMP