I've used Paint Shop Pro 9 in the past. Maybe you already know this, but JPG is a horrible format for images. You will almost always get some image degradation with JPG.
Next thing I want to mention: Paint Shop Pro 9 doesn't work well with large image files.
If I were you my solution would be: Get your hands on Photoshop. It doesn't even have to be the latest and greatest Photoshop, (and stop using JPG if at all possible!). PNG is a pretty good format in my opinion.