You're right: anything that specifically mentions PSCS, or PS Elements you will not be able to use, although you can open psd files (the native PS format) in PSP 9.

Rule of thumb is to stay away from anything software specific. Most kits are compiled of jpg and png files and you will have no problem using those. Hayley64/Tracey Rennemo here has some great PSP scripts, our version of PS Actions, and you will be able to use those, depending upon your version of PSP as some are version specific. Also do not buy brushes that are abr format only: PSP cannot read those. You can buy brushes where there are also png versions, and they can be resized if necessary.

Have fun trying out some kits!

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Jane

Paint Shop Pro X2
Nikon Coolpix/Sony Cybershot