I finally switched to Photoshop after many years of using PhotoImpact.  I got a good deal on PS via my purchase of a Wacom graphics tablet.

One thing I always fought when using PI, most all of the tutorials for 3D graphics applications seemed to use PS as the graphics editor, so I had to try to mimic the instructions in PI.

I guess the best advice is to take your time and ask a lot of questions.  What are you going to use the program for?  Photoshop may be an investment; Paintshop Pro may be a great value and save you some money.

Corel also bought Ulead (PhotoImpact) so there may be a merging of PP and PI ?  Something  to watch and consider.