I have downloaded the trial version of PhotoShop. I also took a free 2 hour intro to photoshop class
at the university. (which was somewhat helpful, but they were running an older verison)
The one thing that photoshop (cs3) had that really impressed me was the "spot heal"
function. Cleaned up a couple of spots on pictures from either dust on the lens or the sensor.
This alone might make it worth it.
Does, says PaintShopPro, have that kind of feature?
Spot Heal/Clone Tool
I don't use spot heal that much but do utilize the clone tool which essentially does the same thing and allows more adjustment. For example - if you have a dust spot in the sky where the color/saturation changes ever so slightly, you can set your opacity to less than 100% and get a more gradual change. I probably use this tool (clone) more than any other.
--Terry