I have to add that PSP has a lot of brushes available to download for free (I have over 400 brushes) just like PSE3. The only thing there I suppose is that since they didn't come preinstalled in PSP that you would have to check out for giving credit to the designers of the brushes. But if you use them in PS you would need to do that also.
Also after searching around I did find a decent amount of preset shapes and there are presets that can be added to your effects that are available to download also.
I think possibly that PSP has the best environment for creating exactly the type of program you need it to be for your usage.
There are scripts also that add a whole other dimension for PSP...
There are also a lot of plug-ins and filters that are free also, most of the earlier one from PS work in PSP, and people are still making new ones that work both in PS and PSP users.
