I'm not a designer so I'm not obliged to use Photoshop. This brings me options and I'm very happy with this, because I don't like Photoshop. There are two main reasons: 1.It's too expensive, 2.It has a large, very large footprint (which means it demands lots of computer resources like memory and processor) .
I also used Paint Shop Pro, and I was quite happy with it until the version 10. But then, it also became a large footprint application.
Provided that if you have options like me, you may consider to use Paint .NET. It's most interesting that, this application is the result of the graduation project of a guy called Rick Brewster. Good work Rick, bravo! I'm using it for more than 6 months and I'm very satisfied with it. Highlights are:
+ It's completely free
+ Small memory and processor consumption
+ Never crashes
+ Provides most features of Photoshop, including layers
+ Has lots of image processing filters
+ Can support all your needs, unless you're a designer
Of course there are lots of Photoshop features that are not implemented here. Your chances of your using this application, totally depends on your needs. For example, you don't have a GIF Export feature. But it doesn't bother me, because I always used simple methods for producing transparent GIFs.
You can download the application from http://www.getpaint.net/